BREAKING! Brazil Researchers Validates That SARS-CoV-2 Utilizes Human Host Protein PCNA For Replication While DNA Of The Host Cells Are Damaged!

A new startling discovery by researchers from the University of Campinas (Unicamp)-Brazil and the University of São Paulo (USP)-Brazil has validated evidence that could have various startling medical and health implications for all those that have been exposed to the SARS-CoV-2 coronavirus.


 
The researchers found that the SARS-CoV-2 virus utilizes the human host protein called PCNA or Proliferating Cell Nuclear Antigen which is typically a biomarker for DNA damage for its own viral replication but at the same time another human host DNA damage biomarker…r γH2AX was also found to be highly expressed during the  virus replication, indicating that the human host cells are undergoing DNA damage!
 
The SARS-CoV-2 virus is an emerging novel virus from the Coronaviridae family and is responsible for the ongoing COVID-19 pandemic.
 
The research team explored the previously reported SARS-CoV-2 structural membrane protein (M) interaction with human Proliferating Cell Nuclear Antigen (PCNA).
https://pubmed.ncbi.nlm.nih.gov/32353859/
 
https://pubmed.ncbi.nlm.nih.gov/33845483/
 
The SARS-CoV-2 M protein is responsible for maintaining virion shape, and PCNA is a marker of DNA damage which is essential for DNA replication and repair.
 
The study team validated the M-PCNA interaction through immunoprecipitation, immunofluorescence co-localization, and PLA (Proximity Ligation Assay).
 
In cells infected with SARS-CoV-2 or transfected with M protein, using immunofluorescence and cell fractioning, the study team documented a reallocation of PCNA from the nucleus to the cytoplasm and the increase of PCNA and γH2AX (another DNA damage marker) expression.
 
The study findings also showed an increase in PCNA and γH2AX expression in the lung of a COVID-19 patient by immunohistochemistry.
 
In addition, the inhibition of PCNA translocation by PCNA I1 and Verdinexor led to a reduction of plaque formation in an in vitro assay.
 
The study team proposes that the transport of PCNA to the cytoplasm and its association with M could be a virus strategy to manipulate cell functions and may be considered a target for COVID-19 therapy.
 
But Thailand Medical News would also like to importantly note that the study findings also confirm that human host DNA is damaged during infections with the SARS-CoV-2 coronavirus. Such cellular DNA damage can have various impacts on the long-term health aspects of the individual infected and can give rise to various serious medical conditions.
 
The study findings were published in the peer reviewed journal: Frontiers in Cellular and Infection Microbiology. https://www.frontiersin.org/articles/10.3389/fcimb.2022.849017/full
 
The study findings were the first to validate how a human protein interacts with a SARS-CoV-2 protein, and describe one of the ways the virus that causes COVID-19 to recruit host cells to repl icate.
 
The study team in laboratory tests, inhibited interaction between the virus and the host proteins using a drug and thereby reduced viral replication by 15%-20%. They expect their findings to contribute to the development of treatments for COVID-19.
 
Principal study investigator, Dr Fernando Moreira Simabuco, Professor at UNICAMP's School of Applied Sciences (FCA) told Thailand Medical News, “The human protein known as PCNA ie proliferating cell nuclear antigen, interacts with the SARS-CoV-2 protein M, one of the molecules that make up the virus's membrane and give it shape. The discovery itself shows one of the ways the pathogen manipulates cell function for its life cycle to proceed."
 
The study team used a range of in vitro techniques to investigate how the presence of the viral protein M in the organism makes PCNA, a protein involved in DNA repair, migrate from the cell nucleus, where it is normally found, to the cytoplasm, a cellular region containing organelles responsible for important cell functions.
 
The study team said that this migration of the protein to the viral replication site shows that the viral and human proteins interact, a conclusion corroborated by other methods, such as use of compounds to inhibit migration of proteins from the nucleus to the cytoplasm.
 
It was found that in cells treated with both a specific compound for PCNA and another that inhibits migration of different proteins including PCNA, viral replication was reduced by between 15% and 20% compared with untreated cells.
 
Professor Simabuco added, "If we'd been thinking about treatment, perhaps this reduction wouldn't have been significant, but our main aim was to demonstrate the interaction and show that it could be a future therapeutic target.”
 
In a research collaboration with scientsts from the Pathology Department of USP's Medical School, the researchers analyzed samples of lung tissue obtained during autopsies of deceased COVID-19 patients. https://agencia.fapesp.br/results-of-covid-19-autopsies-offer-help-with-treatment-of-severe-cases/32955/
 
Interestingly, the expression of PCNA was found to be above normal in these samples, as was expression of the protein gamaH2AX, a marker of DNA damage, reinforcing the results.
 
Professor Simabuco said, "This finding may point to yet another consequence of infection by the virus and confirms that the virus also causes DNA damage to the host cells.”
 
The SARS-CoV-2 M protein is anchored, with proteins E and S, in the membrane that envelops SARS-CoV-2, and is the most abundant of its four main structural proteins, called structural because they give it shape. For this reason, it has been considered a potential target for medications and vaccines.
S, the viral spike protein, is well-known because it binds to the ACE receptor in human cells, a role that has made it the target for most current COVID-19 vaccines.
 
However, it should be noted that as the SARS-CoV-2 virus evolves and mutates… spawning numerous variants, a variety of mutations have also emerged at these M proteins that affects the efficacy of identified potential antivirals. https://www.thailandmedical.news/news/breaking-sars-cov-2-ba-2-variant-spawning-mutations-on-its-mpro-sites-that-reduce-efficacy-of-the-antiviral-paxlovid-many-such-variants-in-america-no
 
The host protein PCNA is widely studied in the context of cancer research, as exemplified by a project conducted by Professor Simabuco at FCA-UNICAMP. Little is known about the role of PCNA in viral infections, however.
 
The study findings therefore, offers a way forward for further research on this interaction between SARS-CoV-2 and PCNA, facilitating the development of therapies. A next step would be validation of the discoveries in animal models, although this has not yet been programmed.
 
For the study, some of the experiments were conducted at the Laboratory of Emerging Virus Studies (LEVE) headed by José Luiz Proença Módena at UNICAMP's Biology Institute (IB), with FAPESP's support.
 
Study groups led by Armando Morais Ventura, a professor at USP's Biomedical Sciences Institute (ICB), and Henrique Marques-Souza, a professor at IB-UNICAMP, collaborated in the study. The first author of the article is Érika Pereira Zambalde, a postdoctoral researcher at FCA-UNICAMP under Simabuco's supervision.
 
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