ACE2

Model Offers New Ways to Study Disease Impact and Treatment Approaches NEW YORK, Nov. 1, 2023 /PRNewswire/ -- Researchers have genetically engineered the first mice that get a human-like form of COVID-19, according to a study published online November 1 in Nature. Led by researchers from NYU Grossman School of Medicine, the new work created lab mice with human genetic material for ACE2 – a protein snagged by the pandemic virus so it can attach to human cells as part of the infection. The mice with this genetic change developed symptoms similar to young humans infected with the virus causing COVID-19, instead of dying upon infection as had occurred with prior mouse models. "That these mice survive creates the first animal model that mimics the form of COVID-19 seen in most people – down to the immune system cells activated and comparable symptoms," said senior study author Jef Boeke, the Sol and Judith Bergstein Director of the Institute for Systems Genetics at NYU Langone Health. "This has been a major missing piece in efforts to develop new drugs against this virus." "Given that mice have been the lead genetic model for decades," added Boeke, "there are thousands of existing mouse lines that can now be crossbred with our humanized ACE2 mice to study how the body reacts differently to the virus in patients with diabetes or obesity, or as people age." Problem of Large DNA The new study revolves around a new method to edit DNA, the 3 billion "letters" of the genetic code that serve as instructions for building our cells and bodies. While famous techniques like CRISPR enable the editing of DNA editing just one or a few letters at a time, some challenges require changes throughout genes that can be up to 2 million letters long. In such cases, it may be more efficient to build DNA from scratch, with far-flung changes made in large swaths of code pre-assembled and then s into a cell in place of its natural counterpart. Because human genes are so complex, Boeke's lab first developed its "genome writing" approach in yeast, one-celled fungi that share many features with human cells but that are simpler and easier to study. More recently, Boeke's team adapted their yeast techniques to the mammalian genetic code, which is made up of not just of genes that encode proteins, but also of many switches that turn on different genes at different levels in different cell types. By studying this poorly understood "dark matter" that regulates genes, the research team was able to design living mice with cells that had more human-like levels of ACE gene activity for the first time. The study authors used yeast cells to assemble DNA sequences of up to 200,000 letters in a single step, and then delivered these "naked" DNAs into mouse embryonic stem cells using their new delivery method, mS. Overcoming the size limits of past methods, mS delivered a humanized mouse model of COVID-19 pathology by "overwriting" 72 kilobases (kb) of mouse Ace2 code with 180 kb of the human ACE2 gene and its regulatory DNA. To accomplish this cross-species swap, the study method cut into a key spot in the DNA code around the natural gene, s in a synthetic counterpart in steps, and with each addition, added a quality control mechanism so that only cells with the synthetic gene survived. The research team then worked with Sang Yong Kim at NYU's Rodent Genome Engineering Lab using a stem cell technique called "tetraploid complementation" to create a living mouse whose cells included the overwritten genes. In addition, the researchers had previously designed a synthetic version of the gene Trp53, the mouse version of the human gene TP53, and s it into mouse cells. The protein encoded by this gene coordinates the cell's response to damaged DNA, and can even instruct cells containing it to die to prevent the build-up of cancerous cells. When this "guardian of the genome" itself becomes faulty, it is a major contributor to human cancers. Whereas the ACE2 experiments had s in an unchanged version of a human gene, the synthetic, s Trp53 gene had been designed to no longer include a combination of molecular code letters – cytosine (C) next to guanine (G) – known to be vulnerable to random, cancer-causing changes. The researchers overwrote key CG "hotspots" with code containing a different DNA letter in adenine (A). "The AG switch left the gene's function intact, but lessened its vulnerability to mutation, with the s to lead to a 10-to-50 fold lower mutation rate," said first author Weimin Zhang, PhD, a post-doctoral scholar in Boeke's lab. "Our goal is to demonstrate in a living test animal that this s to fewer mutations and fewer resulting tumors, and those experiments are being planned." Along with Boeke and Zhang, NYU Langone study authors were Ran Brosh, Aleksandra Wudzinska, Yinan Zhu, Noor Chalhoub, Emily Huang, and Hannah Ashe in the Institute for Systems Genetics and Department of Biochemistry & Molecular Pharmacology; Ilona Golynker, Lucia Carrau, Payal Damani-Yokota, Camille Khairallah, Kamal Khanna, and Benjamin tenOever in the Department of Microbiology; and Matthew Maurano and Sang Yong Kim in the Department of Pathology. The work was funded by National Institutes of Health CEGS grant 1RM1HG009491 and Perlmutter Cancer Center Support Grant P30CA016087. Boeke is a founder of CDI Labs, Inc., a founder of Neochromosome, Inc.; a founder of ReOpen Diagnostics, LLC, and serves or has served on the scientific advisory boards of Logomix Inc., Modern Meadow, Inc., Rome Therapeutics, Inc., Sample6, Inc., Sangamo, Inc., Tessera Therapeutics, Inc. and the Wyss Institute. Boeke also receives consulting fees and royalties from OpenTrons, and holds equity in the company. These relationships are managed in accordance with the policies of NYU. Contact: Gregory Williams [email protected] SOURCE NYU Grossman School of Medicine and NYU Langone Health

The SARS-CoV-2 virus responsible for COVID-19 can cause severe acute respiratory syndrome, contrasting with other coronaviruses that were known to cause mild seasonal colds prior to its emergence in 2019. This raises the question of why one coronavirus affects humans more severely than another. Scientists have now provided part of the answer by identifying a gateway used by the seasonal coronavirus HKU1 to enter human cells. The SARS-CoV-2 virus responsible for COVID-19 can cause severe acute respiratory syndrome, contrasting with other coronaviruses that were known to cause mild seasonal colds prior to its emergence in 2019. This raises the question of why one coronavirus affects humans more severely than another. Scientists at the Institut Pasteur, Université Paris Cité and the VRI have now provided part of the answer by identifying a gateway used by the seasonal coronavirus HKU1 to enter human cells. HKU1 binds to a different receptor than SARS-CoV-2, which may partly explain the difference in severity between these two coronaviruses. Receptors provide a useful means of elucidating coronavirus transmissibility and pathology as part of surveillance work on viral evolution. These results are published in the October 25, 2023 issue of Nature. Seven coronaviruses are known for their ability to infect humans. Four of these are generally mild: HKU1, 229E, NL63 and OC43, while the other three are more pathogenic: SARS-CoV-1, Mers-CoV and SARS-CoV-2. The HKU1 virus was first identified in an elderly patient with severe pneumonia in Hong Kong in 2005. Like SARS-CoV-2, HKU1 mainly infects upper respiratory tract cells. However, it rarely affects the bronchi and alveoli in the lungs. The HKU1 virus causes colds and other mild respiratory symptoms. Complications may also occur, including severe respiratory tract infections, particularly in young children, the elderly and immunocompromised individuals. It is estimated that 70% of children are infected before the age of 6. In total, 75 to 95% of the global population has been exposed to HKU1, which is comparable to other seasonal human coronaviruses. At cellular level, coronavirus spike proteins are cleaved, or split in two, after binding to their receptors. This cleavage phenomenon is vital for viral fusion, entry and multiplication. Some coronaviruses (SARS-CoV-2 and NL63) use the ACE2 receptor as a gateway for entering cells. Until now, HKU1 and OC43 were the only coronaviruses with unknown receptors. Through collaboration between scientists at eight Institut Pasteur units, it was possible to identify the TMPRSS2 enzyme as the receptor to which HKU1 binds to enter cells. Once binding has occurred, TMPRSS2 triggers fusion of HKU1 with the cell, leading to viral infection. Through a combination of techniques performed in vitro and in cell culture, the scientists demonstrated that the TMPRSS2 receptor has high affinity with the HKU1 spike, which is not the case for SARS-CoV-2. "Once a receptor has been identified for a virus, it is possible to characterize target cells more accurately, while also gaining insights on viral entry and multiplication mechanisms and infection pathophysiology," comments, Olivier Schwartz, co-last author of the study and Head of the Institut Pasteur's Virus and Immunity unit. "Our findings also shed light on the various evolution strategies employed by coronaviruses, which use TMPRSS2 either to bind to target cells or trigger fusion and viral entry," adds Julian Buchrieser, co-last author of the study and scientist in the Institut Pasteur's Virus and Immunity unit. These human-pathogenic viruses' use of different receptors probably affects their degree of severity. Receptor levels vary among respiratory tract cells, thus influencing the sensitivity of cells to infection and viral spread. Once the route of viral entry into cells is known, it should also be possible to fight infection more effectively by developing targeted therapies and assess the risk of virulence posed by any future emerging coronaviruses. In parallel with this work, Institut Pasteur teams led by Pierre Lafaye and Felix Rey have developed and characterized nano-antibodies (very small antibodies) that inhibit HKU1 infection by binding to the TMPRSS2 receptor. These reagents have been patented for potential therapeutic activities. This work was funded by the above-mentioned research bodies with additional support from the French Foundation for Medical Research (FRM), ANRS-Emerging Infectious Diseases, Vaccine Research Institute, the European HERA DURABLE project, the Labex IBEID and the ANR/FRM Flash Covid project.

Newly published research proves that it's possible to treat high blood pressure by using specially engineered Lactobacillus paracasei to produce a protein called ACE2 in the gut, reducing gut angiotensin II and, in turn, lowering blood pressure. The study, done in lab rats that are predisposed to hypertension and unable to naturally produce ACE2, opens new doors in the pursuit of harnessing our body's own microbiome to regulate blood pressure. Scientists at The University of Toledo have proven that engineered bacteria can lower blood pressure, a finding that opens new doors in the pursuit of harnessing our body's own microbiome to treat hypertension. The study, published this month in the peer-reviewed journal Pharmacological Research, represents a paradigm shift, said Dr. Bina Joe, a hypertension researcher at UToledo and the paper's senior author. "The question we always ask is, can we exploit microbiota to help our health, for which optimal blood pressure is a cardinal sign. Until now, we have simply said changes in microbiota play a role in elevated blood pressure or hypertension. Those are important findings, but they don't always have an immediately translational application," she said. "This is the first time we have shown that we really can do this. It's a proof of principle that you can use microbiota to make products that measurably improve your health." Joe, a Distinguished University Professor and chair of the Department of Physiology and Pharmacology in the UToledo College of Medicine and Life Sciences, is a pioneer in studying the connection between bacteria living in our gut and blood pressure regulation. In her most recent research, Joe and her team tested Lactobacillus paracasei, a beneficial gut bacterium, that was specially modified to produce a protein called ACE2 in lab rats that are predisposed to hypertension and unable to naturally produce ACE2. ACE2 has drawn considerable interest in recent years because of its role as a key receptor for the virus that causes COVID-19. However, the protein also negatively regulates the renin-angiotensin system which generates angiotensin II, a hormone that raises blood pressure in a number of ways, including by the constriction of blood vessels. By feeding rats the engineered Lactobacillus paracasei bacterium as a probiotic, researchers were able to introduce human ACE2 in their guts, which specifically reduced their gut angiotensin II and, in turn, lowered their blood pressure. Interestingly, though, the blood-pressure-lowering effects were only seen in female rats. Though there was no difference in ACE2 expression between male and female rats, only the female rats saw a decrease in their blood pressure. Researchers are unsure of exactly why that was the case, but Joe speculates it has something to do with the fact that females, but not males, have two functional copies of ACE2. The gene encoding ACE2 is located in a region of the X-chromosome which escapes a genetic phenomenon called X-inactivation. It appears, Joe said, that having two functional copies of ACE2 is extremely important for females, because when both copies were lost, females had a much higher level of hypertension compared to males. "Females therefore appear to readily accept all the help they can get from gut microbiota supplying ACE," she said. "For now, this is a theory that requires further experimental proof." Even with the differing results between male and female rats, however, Joe said the findings are an important steppingstone between the theory of leveraging bacteria to treat hypertension and other chronic conditions and practically being able to bring it into the clinic. "There have been questions about microbiome medicine -- is it a fad or is it real? This is an extremely exciting demonstration that we can exploit bacteria to work for us, and it works for high blood pressure, something that affects a significant portion of the population," she said. "It's that ray of hope that you may not need traditional medications to keep your blood pressure in check." According to data from the U.S. Centers for Disease Control and Prevention, nearly half of U.S. adults have hypertension, and only about one in four of those have their blood pressure under control. Though it rarely exhibits symptoms, uncontrolled blood pressure is a major risk factor for heart attack, stroke and kidney disease. Joe said more research is needed, including studies on what happens when ACE2-producing bacteria are introduced in animals whose bodies already make the protein naturally and any side effects that might come with boosting ACE2 levels in the gut. However, the first-of-its-kind research from UToledo opens a window into the substantial potential of exploiting the bacteria living in our gut for our benefit. "It is a real possibility that we can use bacteria to correct hypertension. This is a big deal, and the concept could be applied to other diseases," she said. "For example, if you are unable to control your sugar, can we have a bacteria make a protein that can lower your blood glucose? There are still a lot of questions that need answered, but now we know the paradigm works."