Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.B1 (angiotensin-converting enzyme 2)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As a major regulator of blood pressure homeostasis, the renin-angiotensin system (RAS) has been the subject of extensive scientific investigation. While the RAS was first discovered more than 100 years ago, several novel components of the system have been identified only in the last decade. One of these newer members of the RAS family is angiotensin-converting enzyme 2 (ACE2). Among the approaches used to establish a physiological role for ACE2 has been the generation of ACE2-null mouse lines using homologous recombination in embryonic stem cells. In the literature, there have been at least three lines of ACE2 knockout mice generated by gene targeting by different investigative groups. Interestingly, there are significant differences in some of the reported phenotypes of these distinct lines, especially with regard to their cardiovascular physiology. In this paper, we will review the results of published experiments using these ACE2-null mouse lines, highlighting similarities and differences in these studies and summarizing their contributions to our understanding of the physiological functions of this novel member of the RAS.
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PMID:Angiotensin-converting enzyme 2 gene targeting studies in mice: mixed messages. 1837 6

The primary targets for SARS-CoV infection are the epithelial cells in the respiratory and intestinal tract. The angiotensin-converting enzyme 2 (ACE-2) has been identified as a functional receptor for SARS-CoV. ACE-2 has been shown to be expressed at the apical domain of polarized Calu-3 cells. In this report, interferon alfacon 1 was examined for inhibitory activities against SARS-CoV on human lung carcinoma epithelial Calu-3 cell line and the other three African green monkey kidney epithelial cell lines. Interferon alfacon 1 demonstrated significant antiviral activity in neutral red uptake assay and virus yield reduction assay. The data might provide an important insight into the mechanism of pathogenesis of SARS-CoV allowing further development of antiviral therapies for treating SARS infections.
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PMID:Interferon alfacon 1 inhibits SARS-CoV infection in human bronchial epithelial Calu-3 cells. 1840 49

Protein absorption in the intestine is mediated by proteases and brush-border peptidases together with peptide and amino acid transporters. Neutral amino acids are generated by a variety of aminopeptidases and carboxypeptidases and are subsequently taken up by the amino acid transporter B(0)AT1 (SLC6A19), which is mutated in Hartnup disorder. Coexpression of B(0)AT1 together with the brush-border carboxypeptidase angiotensin-converting enzyme 2 (ACE2) in Xenopus laevis oocytes led to a dramatic increase of transporter expression at the oocyte surface. Other members of the SLC6 family were not stimulated by coexpression with ACE2. Addition of a peptide containing a carboxyterminal leucine residue to ACE2- and B(0)AT1-coexpressing oocytes caused inward currents due to Na(+)-leucine cotransport, demonstrating the formation of a metabolic complex. Coexpression of the Hartnup disorder causing mutation B(0)AT1(R240Q) showed reduced interaction with ACE2 and its renal paralogue collectrin. This would result in reduced surface expression in both kidney and intestine, thereby explaining the onset of the disorder in individuals carrying this mutation.
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PMID:A protein complex in the brush-border membrane explains a Hartnup disorder allele. 1842 68

It is believed that a novel coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV), was passed from palm civets to humans and caused the epidemic of SARS in 2002 to 2003. The major species barriers between humans and civets for SARS-CoV infections are the specific interactions between a defined receptor-binding domain (RBD) on a viral spike protein and its host receptor, angiotensin-converting enzyme 2 (ACE2). In this study a chimeric ACE2 bearing the critical N-terminal helix from civet and the remaining peptidase domain from human was constructed, and it was shown that this construct has the same receptor activity as civet ACE2. In addition, crystal structures of the chimeric ACE2 complexed with RBDs from various human and civet SARS-CoV strains were determined. These structures, combined with a previously determined structure of human ACE2 complexed with the RBD from a human SARS-CoV strain, have revealed a structural basis for understanding the major species barriers between humans and civets for SARS-CoV infections. They show that the major species barriers are determined by interactions between four ACE2 residues (residues 31, 35, 38, and 353) and two RBD residues (residues 479 and 487), that early civet SARS-CoV isolates were prevented from infecting human cells due to imbalanced salt bridges at the hydrophobic virus/receptor interface, and that SARS-CoV has evolved to gain sustained infectivity for human cells by eliminating unfavorable free charges at the interface through stepwise mutations at positions 479 and 487. These results enhance our understanding of host adaptations and cross-species infections of SARS-CoV and other emerging animal viruses.
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PMID:Structural analysis of major species barriers between humans and palm civets for severe acute respiratory syndrome coronavirus infections. 1844 27

During several months of 2002, severe acute respiratory syndrome (SARS) caused by SARS-coronavirus (SARS-CoV) spread rapidly from China throughout the world, causing more than 800 deaths due to the development of acute respiratory distress syndrome (ARDS), which is the severe form of acute lung injury (ALI). Interestingly, a novel homologue of angiotensin-converting enzyme, termed angiotensin-converting enzyme 2 (ACE2), has been identified as a receptor for SARS-CoV. Angiotensin-converting enzyme and ACE2 share homology in their catalytic domain and provide different key functions in the renin-angiotensin system (RAS). Angiotensin-converting enzyme cleaves angiotensin I to generate angiotensin II, which is a key effector peptide of the system and exerts multiple biological functions, whereas ACE2 reduces angiotensin II levels. Importantly, our recent studies using ACE2 knockout mice have demonstrated that ACE2 protects murine lungs from ARDS. Furthermore, SARS-CoV infections and the Spike protein of the SARS-CoV reduce ACE2 expression. Notably, injection of SARS-CoV Spike into mice worsens acute lung failure in vivo, which can be attenuated by blocking the renin-angiotensin pathway, suggesting that the activation of the pulmonary RAS influences the pathogenesis of ALI/ARDS and SARS.
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PMID:The discovery of angiotensin-converting enzyme 2 and its role in acute lung injury in mice. 1844 62

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a high-risk infectious pathogen. In the proposed model of respiratory failure, SARS-CoV down-regulates its receptor, angiotensin-converting enzyme 2 (ACE2), but the mechanism involved is unknown. We found that the spike protein of SARS-CoV (SARS-S) induced TNF-alpha-converting enzyme (TACE)-dependent shedding of the ACE2 ectodomain. The modulation of TACE activity by SARS-S depended on the cytoplasmic domain of ACE2, because deletion mutants of ACE2 lacking the carboxyl-terminal region did not induce ACE2 shedding or TNF-alpha production. In contrast, the spike protein of HNL63-CoV (NL63-S), a CoV that uses ACE2 as a receptor and mainly induces the common cold, caused neither of these cellular responses. Intriguingly, viral infection, judged by real-time RT-PCR analysis of SARS-CoV mRNA expression, was significantly attenuated by deletion of the cytoplasmic tail of ACE2 or knock-down of TACE expression by siRNA. These data suggest that cellular signals triggered by the interaction of SARS-CoV with ACE2 are positively involved in viral entry but lead to tissue damage. These findings may lead to the development of anti-SARS-CoV agents.
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PMID:Modulation of TNF-alpha-converting enzyme by the spike protein of SARS-CoV and ACE2 induces TNF-alpha production and facilitates viral entry. 1849 Jun 52

Infection of humans with the severe acute respiratory syndrome coronavirus (SARS-CoV) results in substantial morbidity and mortality, with death resulting primarily from respiratory failure. While the lungs are the major site of infection, the brain is also infected in some patients. Brain infection may result in long-term neurological sequelae, but little is known about the pathogenesis of SARS-CoV in this organ. We previously showed that the brain was a major target organ for infection in mice that are transgenic for the SARS-CoV receptor (human angiotensin-converting enzyme 2). Herein, we use these mice to show that virus enters the brain primarily via the olfactory bulb, and infection results in rapid, transneuronal spread to connected areas of the brain. This extensive neuronal infection is the main cause of death because intracranial inoculation with low doses of virus results in a uniformly lethal disease even though little infection is detected in the lungs. Death of the animal likely results from dysfunction and/or death of infected neurons, especially those located in cardiorespiratory centers in the medulla. Remarkably, the virus induces minimal cellular infiltration in the brain. Our results show that neurons are a highly susceptible target for SARS-CoV and that only the absence of the host cell receptor prevents severe murine brain disease.
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PMID:Severe acute respiratory syndrome coronavirus infection causes neuronal death in the absence of encephalitis in mice transgenic for human ACE2. 1849 71

The pathology of severe acute respiratory syndrome-coronavirus (SARS-CoV) infection in cats and ferrets is poorly described, and the distribution of angiotensin-converting enzyme 2 (ACE2), a receptor for SARS-CoV, in the respiratory tracts of these species is unknown. We observed SARS-CoV antigen expression and lesions in the respiratory tracts of 4 cats and 4 ferrets at 4 days postinoculation and ACE2 expression in the respiratory tracts of 3 cats and 3 ferrets without infection. All infected cats and ferrets had diffuse alveolar damage associated with SARS-CoV antigen expression. A novel SARS-CoV-associated lesion was tracheo-bronchoadenitis in cats. SARS-CoV antigen expression occurred mainly in type I and II pneumocytes and serous cells of tracheo-bronchial submucosal glands of cats and in type II pneumocytes of ferrets. ACE2 expression occurred mainly in type I and II pneumocytes, tracheo-bronchial goblet cells, serous epithelial cells of tracheo-bronchial submucosal glands in cats, and type II pneumocytes and serous epithelial cells of tracheo-bronchial submucosal glands in ferrets. In conclusion, the pathology of SARS-CoV infection in cats and ferrets resembles that in humans except that syncytia and hyaline membranes were not observed. The identification of tracheo-bronchoadenitis in cats has potential implications for SARS pathogenesis and SARS-CoV excretion. Finally, these results show the importance of ACE2 expression for SARS-CoV infection in vivo: whereas ACE2 expression in type I and II pneumocytes in cats corresponded to SARS-CoV antigen expression in both cell types, expression of both ACE2 and SARS-CoV antigen in ferrets was limited mainly to type II pneumocytes.
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PMID:Pathology of experimental SARS coronavirus infection in cats and ferrets. 1858 5

The renin-angiotensin system is a far more complex enzymatic cascade than realized previously. Mounting evidence suggests sex-specific differences in the regulation of the renin-angiotensin system and arterial pressure. We examined the hemodynamic responses, angiotensin II receptor subtypes, and angiotensin-converting enzyme 2 gene expression levels after graded doses of angiotensin II in males and females. Mean arterial pressure was measured via telemetry in male and female rats in response to a 2-week infusion of vehicle, low-dose (50 ng/kg per minute SC) or high-dose (400 ng/kg per minute SC) angiotensin II. The effect of concurrent infusion of the angiotensin II type 2 receptor (AT(2)R) blocker (PD123319) was also examined. The arterial pressure response to high-dose angiotensin II was attenuated in females compared with males (24+/-8 mm Hg versus 42+/-5 mm Hg; P for the interaction between sex and treatment <0.002). Remarkably, low-dose angiotensin II decreased arterial pressure (11+/-4 mm Hg; P for the interaction between sex and treatment <0.02) at a dose that did not have an effect in males. This decrease in arterial pressure in females was abolished by AT(2)R blockade. Renal AT(2)R, angiotensin-converting enzyme 2, and left ventricular AT(2)R mRNA gene expressions were markedly greater in females than in males with a renal angiotensin II type 1a receptor:AT(2)R ratio of approximately 1 in females. Angiotensin II infusion did not affect renal AT(2)R mRNA expression but resulted in significantly less left ventricular mRNA expression. Renal angiotensin-converting enzyme 2 mRNA expression levels were greater in females than in males treated with high-dose angiotensin II (approximately 2.5 fold; P for the interaction between sex and treatment <0.05). In females, enhancement of the vasodilatory arm of the renin-angiotensin system, in particular, AT(2)R and angiotensin-converting enzyme 2 mRNA expression, may contribute to the sex-specific differences in response to renin-angiotensin system activation.
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PMID:Enhanced angiotensin II type 2 receptor mechanisms mediate decreases in arterial pressure attributable to chronic low-dose angiotensin II in female rats. 1893 41

The outbreak of severe acute respiratory syndrome (SARS), caused by a distinct coronavirus, in 2003 greatly threatened public health in China, Southeast Asia as well as North America. Over 1,000 patients died of the SARS virus, representing 10% of infected people. Like other coronaviruses, the SARS virus also utilizes a surface glycoprotein, namely the spike protein, to infect host cells. The spike protein of SARS virus consists of 1,255 amino acid residues and can be divided into two sub-domains, S1 and S2. The S1 domain mediates the binding of the virus to its receptor angiotensin-converting enzyme 2, which is abundantly distributed on the surface of human lung cells. The S2 domain mediates membrane fusion between the virus and the host cell. Hence two strategies can be used to block the infection of the SARS virus, either by interfering with the binding of the S1 domain to the receptor or by blocking the fusion of the virus with the cell membrane mediated by the S2 domain. Several antibodies against the S1 domain have been generated and all of them are able to neutralize the virus in vitro and in vivo using animal models. Unfortunately, point mutations have been identified in the S1 domain, so that the virus isolated in the future may not be recognized by these antibodies. As no mutation has been found in the S2 domain indicating that this region is more conserved than the S1 domain, it may be a better target for antibody binding. After predicting the immunogenicity of the epitopes of the S2 domain, we chemically synthesized two peptides and also expressed one of them using a recombinant DNA method. We screened a phage displaying library of human single-chain antibodies (ScFv) against the predicted epitopes and obtained a human ScFv which can recognize the SARS virus in vitro.
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PMID:Development of human single-chain antibodies against SARS-associated coronavirus. 1872 64


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