Project description:The World Health Organization declared the COVID-19 epidemic a public health emergency of international concern on March 11th, 2020, and the pandemic is rapidly spreading worldwide. COVID-19 is caused by a novel coronavirus SARS-CoV-2, which enters human target cells via angiotensin converting enzyme 2 (ACE2). We used a number of bioinformatics tools to computationally characterize ACE2 by determining its cell-specific expression in trachea, lung, and small intestine, derive its putative functions, and predict transcriptional regulation. The small intestine expressed higher levels of ACE2 mRNA than any other organ. By immunohistochemistry, duodenum, kidney and testis showed strong signals, whereas the signal was weak in the respiratory tract. Single cell RNA-Seq data from trachea indicated positive signals along the respiratory tract in key protective cell types including club, goblet, proliferating, and ciliary epithelial cells; while in lung the ratio of ACE2-expressing cells was low in all cell types (<2.6%), but was highest in vascular endothelial and goblet cells. Gene ontology analysis suggested that, besides its classical role in the renin-angiotensin system, ACE2 may be functionally associated with angiogenesis/blood vessel morphogenesis. Using a novel tool for the prediction of transcription factor binding sites we identified several putative binding sites within two tissue-specific promoters of the ACE2 gene as well as a new putative short form of ACE2. These include several interferon-stimulated response elements sites for STAT1, IRF8, and IRF9. Our results also confirmed that age and gender play no significant role in the regulation of ACE2 mRNA expression in the lung.
Project description:The COVID-19 pandemic has caused an unprecedented global public health and economic crisis. The origin and emergence of its causal agent, SARS-CoV-2, in the human population remains mysterious, although bat and pangolin were proposed to be the natural reservoirs. Strikingly, unlike the SARS-CoV-2-like coronaviruses (CoVs) identified in bats and pangolins, SARS-CoV-2 harbors a polybasic furin cleavage site in its spike (S) glycoprotein. SARS-CoV-2 uses human angiotensin-converting enzyme 2 (ACE2) as its receptor to infect cells. Receptor recognition by the S protein is the major determinant of host range, tissue tropism, and pathogenesis of coronaviruses. In an effort to search for the potential intermediate or amplifying animal hosts of SARS-CoV-2, we examined receptor activity of ACE2 from 14 mammal species and found that ACE2s from multiple species can support the infectious entry of lentiviral particles pseudotyped with the wild-type or furin cleavage site-deficient S protein of SARS-CoV-2. ACE2 of human/rhesus monkey and rat/mouse exhibited the highest and lowest receptor activities, respectively. Among the remaining species, ACE2s from rabbit and pangolin strongly bound to the S1 subunit of SARS-CoV-2 S protein and efficiently supported the pseudotyped virus infection. These findings have important implications for understanding potential natural reservoirs, zoonotic transmission, human-to-animal transmission, and use of animal models.IMPORTANCE SARS-CoV-2 uses human ACE2 as a primary receptor for host cell entry. Viral entry mediated by the interaction of ACE2 with spike protein largely determines host range and is the major constraint to interspecies transmission. We examined the receptor activity of 14 ACE2 orthologs and found that wild-type and mutant SARS-CoV-2 lacking the furin cleavage site in S protein could utilize ACE2 from a broad range of animal species to enter host cells. These results have important implications in the natural hosts, interspecies transmission, animal models, and molecular basis of receptor binding for SARS-CoV-2.
Project description:The innate interferon (IFN) response constitutes the first line of host defense against viral infections. It has been shown that IFN-I/III treatment could effectively contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication in vitro. However, how SARS-CoV-2 survives through the innate antiviral mechanism remains to be explored. Our study uncovered that human angiotensin-converting enzyme 2 (ACE2), identified as a primary receptor for SARS-CoV-2 entry, can disturb the IFN-I signaling pathway during SARS-CoV-2 infection in human lung cells. We identified that ACE2 was significantly upregulated by SARS-CoV-2 and Sendai virus (SeV) infection, and exogenous expression of ACE2 suppressed IFN-I production in a dose-dependent manner. Mechanistically, ACE2 disrupted poly (I:C)-mediated inhibition of SARS-CoV2 replication by antagonizing IFN-I production by blocking IRF3 phosphorylation and nuclear translocation. Moreover, ACE2 quenched the IFN-mediated antiviral immune response by degrading endogenous STAT2 protein, inhibiting STAT2 phosphorylation and nuclear translocation. Interestingly, IFN-inducible short ACE2 (dACE2 or MIRb-ACE2) can also be induced by virus infection and inhibits the IFN signaling. Thus, our findings provide mechanistic insight into the distinctive role of ACE2 in promoting SARS-CoV-2 infection and enlighten us that the development of interventional strategies might be further optimized to interrupt ACE2-mediated suppression of IFN-I and its signaling pathway. IMPORTANCE Efficient antiviral immune responses against SARS-CoV-2 infection play a key role in controlling the coronavirus diseases 2019 (COVID-19) caused by this virus. Although SARS-CoV-2 has developed strategies to counteract the IFN-I signaling through the virus-derived proteins, our knowledge of how SARS-CoV-2 survives through the innate antiviral mechanism remains poor. We herein discovered the distinctive role of ACE2 as a restraining factor of the IFN-I signaling in facilitating SARS-CoV-2 infection in human lung cells. Both full-length ACE2 and truncated dACE2 can antagonize IFN-mediated antiviral response. These findings are key to understanding the counteraction between SARS-CoV-2 pathogenicity and the host antiviral defenses.
Project description:Carlina acaulis plant is a potential target for the industrial production of phytochemicals that display applicability in pharmacy and medicine. The dry roots of C. acaulis contain up to 2 % of essential oil, the main component (up to 99 %) of which is carlina oxide [2-(3-phenylprop-1-ynyl)furan]. This compound shows multidirectional biological activity, including antibacterial and antifungal properties. Here, we evaluated the capacity of carlina oxide to inhibit the interaction between SARS-CoV-2 and its human receptor in vitro and in silico. A bioluminescent immunoassay was used to study the interaction between the receptor binding domain (RBD) of viral spike protein and the human angiotensin-converting enzyme 2 (ACE2), which serves as a receptor for viral entry. A dose-effect relationship was demonstrated, and a concentration of carlina oxide causing half-maximal inhibition (IC50) of the RBD:ACE2 interaction was determined to be equal to 234.2 µg/mL. Molecular docking suggested the presence of carlina oxide binding sites within the RBD and at the interface between RBD and ACE2. Finally, this study expands the list of potential applications of C. acaulis as a crop species.
Project description:Hospitalized patients who die from Covid-19 often have pre-existing heart disease. The SARS-CoV-2 virus is dependent on the ACE2 receptor to be able to infect cells. It is possible that the strong link between cardiovascular comorbidities and a poor outcome following a SARS-CoV-2 infection is sometimes due to viral myocarditis. The aim was to examine the expression of ACE2 in normal hearts and hearts from patients with terminal heart failure. The ACE2 expression was measured by global quantitative proteomics and RT-qPCR in left ventricular (LV) tissue from explanted hearts. Immunohistochemistry was used to examine ACE2 expression in cardiomyocytes, fibroblasts and endothelial cells. In total, tissue from 14 organ donors and 11 patients with terminal heart failure were included. ACE2 expression was 2.6 times higher in 4 hearts from patients with terminal heart failure compared with 6 healthy donor hearts. The results were confirmed by immunohistochemistry where more than half of cardiomyocytes or fibroblasts showed expression of ACE2 in hearts from patients with terminal heart failure. In healthy donor hearts ACE2 was not expressed or found in few fibroblasts. A small subpopulation of endothelial cells expressed ACE2 in both groups. Upregulated ACE2 expression in cardiomyocytes may increase the risk of SARS-CoV-2 myocarditis in patients with heart failure.
Project description:SARS-CoV-2, the newly identified human coronavirus causing severe pneumonia pandemic, was probably originated from Chinese horseshoe bats. However, direct transmission of the virus from bats to humans is unlikely due to lack of direct contact, implying the existence of unknown intermediate hosts. Angiotensin converting enzyme 2 (ACE2) is the receptor of SARS-CoV-2, but only ACE2s of certain species can be utilized by SARS-CoV-2. Here, we evaluated and ranked the receptor-utilizing capability of ACE2s from various species by phylogenetic clustering and sequence alignment with the currently known ACE2s utilized by SARS-CoV-2. As a result, we predicted that SARS-CoV-2 tends to utilize ACE2s of various mammals, except murines, and some birds, such as pigeon. This prediction may help to screen the intermediate hosts of SARS-CoV-2.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses its S1 spike protein to bind to angiotensin-converting enzyme 2 (ACE2) on human cells in the first step of cell entry. Tryptanthrin, extracted from leaves of the indigo plant, Polygonum tinctorium, using d-limonene (17.3 µg/ml), is considered to inhibit ACE2-mediated cell entry of another type of coronavirus, HCoV-NL63. The current study examined whether this extract could inhibit the binding of the SARS-CoV-2 spike protein to ACE2. Binding was quantified as cell-bound fluorescence intensity in live cell cultures in which canine kidney MDCK cells overexpressing ACE2 were incubated with fluorescein-labeled S1 spike protein. When indigo extract, together with S1 protein, was added at 8,650x and 17,300x dilutions, fluorescence intensity decreased in a dose- and S1 extract-dependent manner, without affecting cell viability. When 4.0-nM tryptanthrin was added instead of the indigo extract, fluorescence intensity also decreased, but to a lesser degree than with indigo extract. Docking simulation analyses revealed that tryptanthrin readily bound to the receptor-binding domain of the S1 protein, and identified 2- and 7-amino acid sequences as the preferred binding sites. The indigo extract appeared to inhibit S1-ACE2 binding at high dilutions, and evidently contained other inhibitory elements as well as tryptanthrin. This extract may be useful for the prevention or treatment of SARS-CoV-2 infection.
Project description:The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic represents a global threat, and the interaction between the virus and angiotensin-converting enzyme 2 (ACE2), the primary entry receptor for SARS-CoV-2, is a key determinant of the range of hosts that can be infected by the virus. However, the mechanisms underpinning ACE2-mediated viral entry across species remains unclear. Using infection assay, we evaluated SARS-CoV-2 entry mediated by ACE2 of 11 different animal species. We discovered that ACE2 of Rhinolophus sinicus (Chinese rufous horseshoe bat), Felis catus (domestic cat), Canis lupus familiaris (dog), Sus scrofa (wild pig), Capra hircus (goat), and Manis javanica (Malayan pangolin) facilitated SARS-CoV-2 entry into nonsusceptible cells. Moreover, ACE2 of the pangolin also mediated SARS-CoV-2 entry, adding credence to the hypothesis that SARS-CoV-2 may have originated from pangolins. However, the ACE2 proteins of Rhinolophus ferrumequinum (greater horseshoe bat), Gallus gallus (red junglefowl), Notechis scutatus (mainland tiger snake), or Mus musculus (house mouse) did not facilitate SARS-CoV-2 entry. In addition, a natural isoform of the ACE2 protein of Macaca mulatta (rhesus monkey) with the Y217N mutation was resistant to SARS-CoV-2 infection, highlighting the possible impact of this ACE2 mutation on SARS-CoV-2 studies in rhesus monkeys. We further demonstrated that the Y217 residue of ACE2 is a critical determinant for the ability of ACE2 to mediate SARS-CoV-2 entry. Overall, these results clarify that SARS-CoV-2 can use the ACE2 receptors of multiple animal species and show that tracking the natural reservoirs and intermediate hosts of SARS-CoV-2 is complex.
Project description:The coronavirus disease 2019 (COVID-19) first appeared in December 2019 and rapidly spread throughout the world. The SARS-CoV-2 virus enters the host cells by binding to the angiotensin-converting enzyme 2 (ACE2). Although much of the focus is on respiratory symptoms, recent reports suggest that SARS-CoV-2 can cause pregnancy complications such as pre-term birth and miscarriages; and women with COVID-19 have had maternal vascular malperfusion and decidual arteriopathy in their placentas. Here, we report that the ACE2 protein is expressed in both endometrial epithelial and stromal cells in the proliferative phase of the menstrual cycle, and the expression increases in stromal cells in the secretory phase. It was observed that the ACE2 mRNA and protein abundance increased during primary human endometrial stromal cell (HESC) decidualization. Furthermore, HESCs transfected with ACE2-targeting siRNA impaired the full decidualization response, as evidenced by a lack of morphology change and lower expression of the decidualization markers PRL and IGFBP1. Additionally, in mice during pregnancy, the ACE2 protein was expressed in the uterine epithelial cells, and stromal cells increased through day 6 of pregnancy. Finally, progesterone induced Ace2 mRNA expression in mouse uteri more than vehicle or estrogen. These data establish a role for ACE2 in endometrial physiology, suggesting that SARS-CoV-2 may be able to enter endometrial stromal cells and elicit pathological manifestations in women with COVID-19, including an increased risk of early pregnancy loss.
Project description:There are currently few approved effective treatments for SARS-CoV-2, the virus responsible for the COVID-19 pandemic. Nanobodies are 12-15 kDa single-domain antibody fragments that can be delivered by inhalation and are amenable to relatively inexpensive large scale production compared to other biologicals. We have isolated nanobodies that bind to the SARS-CoV-2 spike protein receptor binding domain and block spike protein interaction with the angiotensin converting enzyme 2 (ACE2) with 1-5 nM affinity. The lead nanobody candidate, NIH-CoVnb-112, blocks SARS-CoV-2 spike pseudotyped lentivirus infection of HEK293 cells expressing human ACE2 with an EC50 of 0.3 µg/mL. NIH-CoVnb-112 retains structural integrity and potency after nebulization. Furthermore, NIH-CoVnb-112 blocks interaction between ACE2 and several high affinity variant forms of the spike protein. These nanobodies and their derivatives have therapeutic, preventative, and diagnostic potential.