Tag Archives: Biochemistry

Co-infection with MRSA ‘superbug’ could make COVID-19 outcomes even more deadly

Global data shows nearly 10 per cent of severe COVID-19 cases involve a secondary bacterial co-infection – with Staphylococcus aureus, also known as Staph A., being the most common organism responsible for co-existing infections with SARS-CoV-2. Researchers at Western have found if you add a ‘superbug’ – methicillin-resistant Staphylococcus aureus (MRSA) – into the mix, the COVID-19 outcome could be even more deadly.

The mystery of how and why these two pathogens, when combined, contribute to the severity of the disease remains unsolved. However, a team of Western researchers has made significant progress toward solving this “whodunit”.

New research by Mariya Goncheva, Richard M. Gibson, Ainslie C. Shouldice, Jimmy D. Dikeakos and David E. Heinrichs, has revealed that IsdA, a protein found in all strains of Staph A., enhanced SARS-CoV-2 replication by 10- to 15-fold. The findings of this study are significant and could help inform the development of new therapeutic approaches for COVID-19 patients with bacterial co-infections.

Interestingly, the study, which was recently published in iScience, also showed that SARS-CoV-2 did not affect the bacteria’s growth. This was contrary to what the researchers had initially expected.

We started with an assumption that SARS-CoV-2 and hospitalization due to COVID-19 possibly caused patients to be more susceptible to bacterial infections which eventually resulted in worse outcomes.”

Mariya Goncheva

Goncheva is a former postdoctoral associate, previously with the department of microbiology and immunology at Schulich School of Medicine & Dentistry.

Goncheva said bacterial infections are most commonly acquired in hospital settings and hospitalization increases the risk of co-infection. “Bacterial infections are one of the most significant complications of respiratory viral infections such as COVID-19 and Influenza A. Despite the use of antibiotics, 25 per cent of patients co-infected with SARS-CoV-2 and bacteria, die as a result. This is especially true for patients who are hospitalized, and even more so for those in intensive care units. We were interested in finding why this happens,” said Goncheva, lead investigator of the study.

Goncheva, currently Canada Research Chair in virology and professor of biochemistry and microbiology at the University of Victoria, studied the pathogenesis of multi-drug resistant bacteria (such as MRSA) supervised by Heinrichs, professor of microbiology and immunology at Schulich Medicine & Dentistry.

When the COVID-19 pandemic hit, she pivoted to study interactions between MRSA and SARS-CoV-2.

For this study, conducted at Western’s level 3 biocontainment lab, Imaging Pathogens for Knowledge Translation (ImPaKT), Goncheva’s work created an out-of-organism laboratory model to study the interactions between SARS-CoV-2 and MRSA, a difficult-to-treat multi-drug resistant bacteria.

“At the beginning of the pandemic, the then newly opened ImPaKT facility made it possible for us to study the interactions between live SARS-CoV-2 virus and MRSA. We were able to get these insights into molecular-level interactions due to the technology at ImPaKT,” said Heinrichs, whose lab focuses on MRSA and finding drugs to treat MRSA infections. “The next step would be to replicate this study in relevant animal models.”

Source:
Journal reference:

Goncheva, M. I., et al. (2023). The Staphylococcus aureus protein IsdA increases SARS CoV-2 replication by modulating JAK-STAT signaling. IScience. doi.org/10.1016/j.isci.2023.105975.

The Extraordinary “Rapunzel” Virus: An Evolutionary Marvel

Extremely long tail provides a window into how bacteria-infecting viruses assemble.

A recent study in the Journal of Biological Chemistry has revealed the secret behind an evolutionary marvel: a bacteriophage with an extremely long tail. This extraordinary tail is part of a bacteriophage that lives in inhospitable hot springs and preys on some of the toughest bacteria on the planet.

Bacteriophages are a group of viruses that infect and replicate in bacteria and are the most common and diverse things on Earth.

“Bacteriophages, or phages for short, are everywhere that bacteria are, including the dirt and water around you and in your own body’s microbial ecosystem as well,” said Emily Agnello, a graduate student at the University of Massachusetts Chan Medical School and the lead author on the study.

Unlike many of the viruses that infect humans and animals that contain only one compartment, phages consist of a tail attached to a spiky, prismlike protein shell that contains their DNA.

Phage tails, like hairstyles, vary in length and style; some are long and bouncy while others are short and stiff. While most phages have short, microscopic tails, the “Rapunzel bacteriophage” P74-26 has a tail 10 times longer than most and is nearly 1 micrometer long, about the width of some spider’s silk. The “Rapunzel” moniker is derived from the fairy tale in which a girl with extremely long hair was locked in a tower by an evil witch.

Brian Kelch, an associate professor of biochemistry and molecular biotechnology at UMass Chan who supervised the work, described P74-26 as having a “monster of a tail.”

Phage tails are important for puncturing bacteria, which are coated in a dense, viscous substance. P74-26’s long tail allows it to invade and infect the toughest bacteria. Not only does P74-26 have an extremely long tail, but it is also the most stable phage, allowing it to exist in and infect bacteria that live in hot springs that can reach over 170° F. Researchers have been studying P74-26 to find out why and how it can exist in such extreme environments.

To work with a phage that thrives in such high temperatures, Agnello had to adjust the conditions of her experiments to coax the phage tail to assemble itself in a test tube. Kelch said Agnello created a system with which she could induce rapid tail self-assembly.

“Each phage tail is made up of many small building blocks that come together to form a long tube. Our research finds that these building blocks can change shape, or conformation, as they come together,” Agnello said. “This shape-changing behavior is important in allowing the building blocks to fit together and form the correct structure of the tail tube.”

The researchers used high-power imaging techniques as well as computer simulations and found that the building blocks of the tail lean on each other to stabilize themselves.

“We used a technique called cryo-electron microscopy, which is a huge microscope that allows us to take thousands of images and short movies at a very high magnification,” Agnello explained. “By taking lots of pictures of the phage’s tail tubes and stacking them together, we were able to figure out exactly how the building blocks fit together.”

They found P74-26 uses a “ball and socket” mechanism to sturdy itself. In addition, the tail is formed from vertically stacking rings of molecules that make a hollow canal.

“I like to think about these phage building blocks as kind of like Legos,” Kelch said. “The Lego has studs on one side and the holes or sockets on the other.”

He added: “Imagine a Lego where the sockets start off closed. But as you start to build with the Legos, the sockets begin to open up to allow the studs on other Legos to build a larger assembly. This movement is an important way that these phage building blocks self-regulate their assembly.”

Kelch pointed out that, compared with most phages, P74-26 uses half the number of building blocks to form stacking rings that make up the tail.

“We think what has happened is that some ancient virus fused its building blocks into one protein. Imagine two small Lego bricks are fused into one large brick with no seams. This long tail is built with larger, sturdier building blocks,” Kelch explained. “We think that could be stabilizing the tail at high temperatures.”

The researchers now plan to use genetic manipulation to alter the length of the phage tail and see how that changes its behavior.

Phages occupy almost every corner of the globe and are important to a variety of industries like healthcare, environmental conservation and food safety. In fact, long-tailed phages like P74-26 have been used in preliminary clinical trials to treat certain bacterial infections.

“Bacteriophages are gaining ever-growing interest as an alternative to antibiotics for treating bacterial infections,” Agnello said. “By studying phage assembly, we can better understand how these viruses interact with bacteria, which could lead to the development of more effective phage-based therapies. … I believe that studying unique, interesting things can lead to findings and applications that we can’t even yet imagine.”

Reference: “Conformational dynamics control assembly of an extremely long bacteriophage tail tube” by Emily Agnello, Joshua Pajak, Xingchen Liu and Brian A. Kelch, 14 March 2023, Journal of Biological Chemistry.
DOI: 10.1016/j.jbc.2023.103021

Study finds two substances capable of inhibiting proliferation of glioblastoma cells

Glioblastoma is a malignant tumor of the central nervous system (brain or spinal cord) and one of the deadliest types of cancer. Few drugs have proved effective at combating this uncontrolled growth of glial cells, which anyway constitute a large proportion of the brain tissue in mammals. The standard treatment is surgical removal of the tumor, followed by chemotherapy with temozolomide, radiation therapy, and then nitrosoureas (such as lomustine). Patient survival has improved moderately over the years, but the prognosis remains poor. These tumors are typically resistant to existing drugs and often grow back after surgery.

Promising results have now been reported in a study involving two substances found to inhibit proliferation of glioblastoma cells. An article on the study is published in the journal Scientific Reports.

The researchers conducted in vitro tests to evaluate the biological effects of 12 compounds obtained through total synthesis of apomorphine hydrochloride against glioblastoma cells. They found that two of these compounds – an isoquinoline derivative called A5 and an aporphine derivative called C1 – reduced the viability of glioblastoma cells, suppressed the formation of new tumor stem cells and boosted the effectiveness of temozolomide.

More research is needed to glean a better understanding of the action of these compounds on tumor cells and normal cells, but the results so far suggest a potential therapeutic application as novel cytotoxic agents to control glioblastomas.”

Dorival Mendes Rodrigues-Junior, first author of the article and postdoctoral researcher, University of Uppsala’s Department of Medical Biochemistry and Microbiology, Sweden

In designing the study, the researchers leveraged the apomorphine hydrochloride production process, in which each step in a sequence of chemical reactions creates compounds that are consumed in the next step. Previous research conducted by the group to evaluate the effectiveness of 14 of these compounds against head and neck squamous cell cancer had shown that A5 and C1 were promising, and they decided to conduct more tests. “Given the importance and urgency of identifying novel therapeutic substances that can be used to treat glioblastoma, we evaluated the same panel as in the previous study but now for this other type of tumor,” Rodrigues-Junior said.

The project on molecular markers of head and neck cancer was supported by FAPESP and also involved André Vettore, another author of the recently published article. Vettore is a professor in the Department of Biological Sciences at the Federal University of São Paulo (UNIFESP) in Diadema, Brazil.

“The findings of this study are interesting, but they’re only the first steps in a long journey. In vivo studies are still required to confirm the effects of A5 and C1 on glioblastoma cells and non-tumorigenic nerve cells,” Vettore said.

If the results of this future research are also promising, he added, it will be possible to move on to clinical trials to confirm the effectiveness of the compounds. “Once all these stages are completed, the compounds may finally be used to treat glioblastoma patients.”

Natural bioactive products

The study was conducted in vitro to evaluate the antitumor activity of 12 aromatic compounds obtained as intermediates in total synthesis of apomorphine, an alkaloid that interacts with the dopamine pathway and is widely used to control the motor alterations caused by Parkinson’s disease.

Alkaloids are a well-known class of natural products with multiple pharmacological properties and are studied for their anticonvulsant, antiplatelet aggregation, anti-HIV, dopaminergic, antispasmodic and anticancer effects.

FAPESP fosters studies of these substances via a project on bioactive natural products led at UNIFESP’s Department of Chemistry in Diadema by Cristiano Reminelli, second author of the Scientific Reports article. The other authors are Haifa Hassanie, Gustavo Henrique Goulart Trossini, Givago Prado Perecim, Laia Caja and Aristidis Moustakas.

Source:
Journal reference:

Rodrigues-Junior, D.M., et al. (2023) Aporphine and isoquinoline derivatives block glioblastoma cell stemness and enhance temozolomide cytotoxicity. Scientific Reports. doi.org/10.1038/s41598-022-25534-2.

Antibiotics can destroy many types of bacteria, but increasingly, bacterial pathogens are gaining resistance to many commonly used …

Antibiotics can destroy many types of bacteria, but increasingly, bacterial pathogens are gaining resistance to many commonly used types. As the threat of antibiotic resistance looms large, researchers have sought to find new antibiotics and other ways to destroy dangerous bacteria. But new antibiotics can be extremely difficult to identify and test. Bacteriophages, which are viruses that only infect bacterial cells, might offer an alternative. Bacteriophages (phages) were studied many years ago, before the development of antibiotic drugs, and they could help us once again.

Image credit: Pixabay

If we are going to use bacteriophages in the clinic to treat humans, we should understand how they work, and how bacteria can also become resistant to them. Microbes are in an arms race with each other, so while phages can infect bacteria, some bacterial cells have found ways to thwart the effects of those phages. New research reported in Nature Microbiology has shown that when certain bacteria carry a specific genetic mutation, phages don’t work against them anymore.

In this study, the researchers used a new technique so they could actually see a phage attacking bacteria. Mycobacteriophages infect Mycobacterial species, including the pathogens Mycobacterium tuberculosis and Mycobacterium abscessus, as well as the harmless Mycobacterium smegmatis, which was used in this research.

The scientists determined that Mycobacterial gene called lsr2 is essential for many mycobacteriophages to successfully infect Mycobacteria. Mycobacteria that carry a mutation that renders the Lsr2 protein non-functional are resistant to these phages.

Normally, Lsr2 aids in DNA replication in bacterial cells. Bacteriophages can harness this protein, however, and use it to reproduce the phage’s DNA. Thus, when Lsr2 stops working, the phage cannot replicate and it cannot manipulate bacterial cells.

In the video above, by first study author Charles Dulberger, a genetically engineered mutant phage infects Mycobacterium smegmatis. First, one phage particle (red dot at 0.42 seconds) binds to a bacterium. The phage DNA (green fluorescence) is injected into the bacterial cell (2-second mark). The bright green dots at the cells’ ends are not relevant. For a few seconds, the DNA forms a zone of phage replication, and fills the cell. Finally, the cell explodes at 6:25 seconds. (About three hours have been compressed to make this video.)

The approach used in this study can also be used to investigate other links between bacteriophages and the bacteria they infect.

“This paper focuses on just one bacterial protein,” noted co-corresponding study author Graham Hatfull, a Professor at the University of Pittsburgh. But there are many more opportunities to use this technique. “There are lots of different phages and lots of other proteins.”

Sources: University of Pittsburgh, Nature Microbiology


Carmen Leitch

Streptococcus pyogenes, which is often called group A Streptococcus, infects people around the world. While estimates vary, these …

Streptococcus pyogenes, which is often called group A Streptococcus, infects people around the world. While estimates vary, these infections could be responsible for the deaths of over half a million individuals every year. The pathogen can also cause an illness known as scarlet fever, which usually occurs in kids between the ages of 5 and 15. Scarlet fever was once a major health threat for children, and there were infection rates as high as 20 percent in the early 20th century. The disease became less of a public health concern until its recent reemergence in the UK, Hong Kong, and mainland China.

Colorized scanning electron micrograph of Group A Streptococcus (Streptococcus pyogenes) bacteria (blue) and a human neutrophil (purple). Credit: NIAID

Isolates taken from patients have shown that S. pyogenes can carry resistance genes that shield it from the effects of antibiotics including tetracycline, erythromycin and clindamycin. These bacteria can also generate powerful toxins, like molecules called SSA and SpeC, known as superantigens, and an enzyme called Spd1.

While S. pyogenes infections are still rare, they can kill as many as 20 percent of people who are infected.

In 2019, a variant isolated in the UK, the so-called M1UK strep A variant, was shown to produce five times more strep A toxins compared to previous strains. The SpeA superantigen generated by this variant can short-circuit host immunity and was once known as the scarlet fever toxin. The M1UK variant also carried a few genetic mutations compared to previous strains, and one of those mutations was located close to the toxin gene. The findings have been reported in Nature Communications.

More research will be needed to know whether this variant has gotten better at moving from one person to another to cause infection.

Strep A is very rare, and the study authors noted that people should not be concerned about this novel variant at this time. Basic hygiene practices, like hand washing, can still protect us from dangerous germs like S. pyogenes. Strep A infections are spread through close contact with infected people, who may be coughing and sneezing. Other symptoms include a rash and fever.

The study authors also noted that these findings have highlighted the importance of developing a vaccine for Strep A infections.

An unrelated study reported in mBio has also revealed a different mutation that occurs in a Strep A variant that increases the production of a toxin called streptolysin O (SLO). SLO can help Strep A survive in the host, evade host immunity, and is destructive to host tissues. Variants that did not express SLO were not as virulent, noted the study authors.

Right now, scientists are working on a Strep A vaccine, as described in the video above.

Sources: Nature Communications, Griffith University, mBio


Carmen Leitch

Infections with many different types of bacteria including Streptococcus pneumonia, Listeria monocytogens, and Neisseria mengitidis can cause bacterial …

Infections with many different types of bacteria including Streptococcus pneumonia, Listeria monocytogens, and Neisseria mengitidis can cause bacterial meningitis. It’s estimated that every year over 1.2 million cases of bacterial meningitis happen around the world, and without treatment, this deadly disease is fatal to seven of ten people who are sickened by it. Even with antibiotic treatments, three of ten patients die. Survivors are left with issues like chronic headaches, seizures, loss of vision or hearing, and other neurological consequences. New research reported in Nature has revealed how bacteria are able to penetrate the meninges that surround and protect the brain to cause bacterial meningitis. The findings have shown that bacteria use neurons to evade immunity and infect the brain, and the work may aid in the creation of new therapeutics.

A digitally-colorized SEM image depicts of Streptococcus pneumoniae bacteria (lavender), as they were being attacked by a white blood cell (pink).  / Credit: CDC/ Dr. Richard Facklam

Right now, antibiotics can help eliminate the bacterial pathogens that cause this illness. But steroids are also needed to control the dangerous inflammation that can occur along with the infection. However, reducing inflammation also weakens the immune response, making it harder to get rid of the infection.

In this research, the scientists used Streptococcus pneumoniae and Streptococcus agalactiae bacteria, which can both cause bacterial meningitis in humans. They determined that when these bacteria get to the meninges, they release a toxin, which activates neurons in the meninges that sense pain. This pain neuron activation could explain why bacterial meningitis patients get horrible headaches, noted the researchers.

The activated pain neurons then release a signaling molecule called CGRP, which binds to a receptor called RAMP1 on the surface of immune cells called macrophages. Once CGRP binds to RAMP1 on macrophages, the immune cells are basically disabled, and they stop responding to bacterial infections like they normally would.

The link between CGRP and RAMP1 on macrophages also stops them from signaling to other immune cells, which allows the bacterial infection to not only penetrate the meninges but to spread infection.

This work was confirmed with the use of a mouse model that lacked the pain neurons that are activated by bacteria. Compared to mice with those neurons, the engineered mice had less severe brain infections when they were exposed to bacteria that cause meningitis. There were also lower levels of CGRP in the engineered mice compared to normal mice. The normal mice, however, had higher levels of bacteria in the meninges.

Additional experiments also showed that when mice were treated with drugs that block RAMP1, the severity of the bacterial infection was reduced. Mice treated with RAMP1 blockers were able to clear their infections faster too.

It may be possible to help the immune system clear cases of bacterial meningitis with medications that block either CGRP or RAMP1, potentially in conjunction with antibiotics. There are already drugs that can do this, and they are generally used to treat migraine.

Sources: Harvard Medical School, Nature


Carmen Leitch

The SARS-CoV-2 virus and the illness it causes, COVID-19, have made an indelible mark on our lives. It …

The SARS-CoV-2 virus and the illness it causes, COVID-19, have made an indelible mark on our lives. It seems that is also true in more ways than one; new research has shown that when the virus infects cells, portions of the viral genome integrate into the genome of host cells in a phenomenon known as reverse transcription. While this is a relatively rare even for SARS-CoV-2, so many people have been infected with the virus that integration has probably happened many times. Scientists have now used several techniques to show that SARS-CoV-2 can integrate into a host cell genome, and the findings have been reported in the journal Viruses. This study is confirmation of previous work reported in the Proceedings of the National Academy of Sciences in 2021.

Colorized scanning electron micrograph of a cell (red) infected with the Omicron strain of SARS-CoV-2 virus particles (blue), isolated from a patient sample. Image captured at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID

This research may help explain why some people continue to test positive for the virus long after their infection has subsided and they have recovered. In reverse transcription, RNA molecules, in this case from SARS-CoV-2, are transcribed into cDNA, a flip of the typical process in which active genes are transcribed into RNA molecules. Those reverse-transcribed cDNA molecules are then stitched into the host cell genome. If some of those cells are captured during a COVID-19 test, PCR would recognize and amplify the viral DNA in the host cell, causing a positive test result.

This study has also shown that simply inserting viral RNA into cells is not enough to cause genomic integration, so it seems unlikely based on the evidence we have now that mRNA from the COVID-19 vaccines would cause integration into cells’ DNA.

“This paper puts our data on a very firm footing. Hopefully, it will clarify some of the issues raised in the discussion that followed the first paper, and provide some reassurance to people who were worried about the implications for the vaccine,” said corresponding study author Rudolf Jaenisch, a founding member of the Whitehead Institute.

Since the integration of the SARS-CoV-2 genome into cells’ DNA is unusual, the researchers had to use a very sensitive method called digital PCR, which detects very specific genetic sequences, to identify instances in which viral RNA had been integrated into the genome of a cell.

The digital PCR results found viral RNA that had been reverse-transcribed to cDNA in about 4 to 20 of every 1,000 cells, but this includes all molecules of the sort, whether they ended up being integrated into a genome or not. Thus, the researchers suggested that viral integration is even more rare than that.

Whole genome sequencing can be used to show when that integration also occurred, because those events are typically accompanied by a reverse transcription complex called LINE1. The LINE1 sequences act as an indicator of integration. However, WGS is usually only used on a handful of cells, so when other investigators looked for those sequences, they could not usually be found.

“Because the human cell genome coverage by whole genome sequencing is very limited, you would need to run the sequencing experiment many times in order to have a good chance of detecting one viral genome copy,” explained postdoctoral researcher and first study author Liguo Zhang.

In this study, the researchers created cells that would overexpress LINE1, and make viral integration more common artificially. This time, the digital PCR showed that viral cDNA appeared in fourteen to twenty of every 1,000 cells, and WGS identified instances of integration along with LINE1. Further work with a tool called TagMap confirmed viral integration without overexpressing LINE1.

“This is unambiguous proof of viral genomic integration,” Zhang said. When this approach was repeated with cells that were treated with SARS-CoV-2 vaccine, there was no evidence of integration.

“We need to do further testing, but our results are consistent with vaccine RNA not integrating,” Jaenisch said.

Sources: Whitehead Institute for Biomedical Research, Viruses


Carmen Leitch

Scientists have found that a gene that has been previously identified in many animals and their associated microbes …

Scientists have found that a gene that has been previously identified in many animals and their associated microbes can enable resistance to antimicrobial drugs. The resistance gene encodes for an enzyme called EstT, which can deactivate antibiotic drugs known as macrolides. The enzyme can disrupt the chemical ring structure of these antibiotics through hydrolysis. When the ring is broken or opened with water, the antibiotic loses both its active shape, and its target affinity, explained study leader Dr. Tony Ruzzini PhD, an assistant professor at the Western College of Veterinary Medicine (WCVM) of the University of Saskatchewan. The findings have been reported in the Proceedings of the National Academy of Sciences.

Image credit: Pixabay

This gene can take macrolide antibiotics out of commission, and illnesses can no longer be treated effectively. Macrolides such as tylosin, tilmicosin and tildipirosin are often used to treat cattle with bovine respiratory disease or liver abscesses, and may also be used to treat other diseases in livestock and companion animals.

In this study, the researchers analyzed genes that were found within microbes that were living in watering bowls at a beef cattle feedlot in western Canada. The investigators isolated the microbes that were in the water, and compared the genes in the microbes to databases of antimicrobial resistance genes.

A bacterium called Sphingobacterium faecium WB1 was found to carry the EstT gene, which was contained within a cluster of three antibiotic resistance genes (ARGs). It was also near plasmids and retrotransposons, suggesting it can move easily from one microbe to another. EstT is commonly found in microbes in the human microbiome too.

“This gene, even though we found it in an environmental organism, it is also present in pathogens that are responsible for causing bovine respiratory disease,” noted Ruzzini.

“Our finding adds to the considerable database of ARGs, which can be crossmatched to a bacteria’s DNA to determine if the bacterium has the potential to be resistant to a particular antimicrobial,” said first study author Dr. Poonam Dhindwal PhD, a postdoctoral fellow at WCVM.

The researchers are continuing to study EstT to learn more about how it works.

“As [antimicrobial resistance] surveillance systems rely more on molecular tools for detection, our knowledge of this specific gene and its integration into those systems will help to better inform antimicrobial use,” said Ruzzini.

Sources: University of Saskatchewan, Proceedings of the National Academy of Sciences (PNAS)


Carmen Leitch

Simple blood tests for telomeric protein could provide a valuable screen for certain cancers

Once thought incapable of encoding proteins due to their simple monotonous repetitions of DNA, tiny telomeres at the tips of our chromosomes seem to hold a potent biological function that’s potentially relevant to our understanding of cancer and aging.

Reporting in the Proceedings of the National Academy of Science, UNC School of Medicine researchers Taghreed Al-Turki, PhD, and Jack Griffith, PhD, made the stunning discovery that telomeres contain genetic information to produce two small proteins, one of which they found is elevated in some human cancer cells, as well as cells from patients suffering from telomere-related defects.

Based on our research, we think simple blood tests for these proteins could provide a valuable screen for certain cancers and other human diseases. These tests also could provide a measure of ‘telomere health,’ because we know telomeres shorten with age.”

Jack Griffith, PhD, the Kenan Distinguished Professor of Microbiology and Immunology and Member of the UNC Lineberger Comprehensive Cancer Center

Telomeres contain a unique DNA sequence consisting of endless repeats of TTAGGG bases that somehow inhibit chromosomes from sticking to each other. Two decades ago, the Griffith laboratory showed that the end of a telomere’s DNA loops back on itself to form a tiny circle, thus hiding the end and blocking chromosome-to-chromosome fusions. When cells divide, telomeres shorten, eventually becoming so short that the cell can no longer divide properly, leading to cell death.

Scientist first identified telomeres about 80 years ago, and because of their monotonous sequence, the established dogma in the field held that telomeres could not encode for any proteins, let alone ones with potent biological function.

In 2011 a group in Florida working on an inherited form of ALS reported that the culprit was an RNA molecule containing a six-base repeat which by a novel mechanism could generate a series of toxic proteins consisting of two amino acids repeating one after the other. Al-Turki and Griffith note in their paper a striking similarity of this RNA to the RNA generated from human telomeres, and they hypothesized that the same novel mechanism might be in play.

They conducted experiments – as described in the PNAS paper – to show how telomeric DNA can instruct the cell to produce signaling proteins they termed VR (valine-arginine) and GL (glycine-leucine). Signaling proteins are essentially chemicals that trigger a chain reaction of other proteins inside cells that then lead to a biological function important for health or disease.

Al-Turki and Griffith then chemically synthesized VR and GL to examine their properties using powerful electron and confocal microscopes along with state-of-the-art biological methods, revealing that the VR protein is present in elevated amounts in some human cancer cells, as well as cells from patients suffering from diseases resulting from defective telomeres.

“We think it’s possible that as we age, the amount of VR and GL in our blood will steadily rise, potentially providing a new biomarker for biological age as contrasted to chronological age,” said Al-Turki, a postdoctoral researcher in the Griffith lab. “We think inflammation may also trigger the production of these proteins.”

Griffith noted, “When you go against current thinking, you are usually wrong because you are bucking many people who’ve worked so diligently in their fields. But occasionally scientists have failed to put observations from two very distant fields together and that’s what we did. Discovering that telomeres encode two novel signaling proteins will change our understanding of cancer, aging, and how cells communicate with other cells.

“Many questions remain to be answered, but our biggest priority now is developing a simple blood test for these proteins. This could inform us of our biological age and also provide warnings of issues, such as cancer or inflammation.”

Source:
Journal reference:

Al-Turki, T., et al. (2023) Mammalian Telomeric RNA (TERRA) can be translated to produce valine-arginine and glycine-leucine dipeptide repeat proteins. PNAS. doi.org/10.1073/pnas.2221529120.

UTHSC researchers secure $308,000 grant from Department of Defense for dementia study

Repeated traumatic brain injuries (TBI) in soldiers and military personnel can cause behavioral, neurological, and cognitive effects and lead to dementia. There is currently no treatment for that type of dementia, but a $308,000 grant from the United States Department of Defense aims to help researchers at the University of Tennessee Health Science Center find one.

TBI can lead to the development of frontotemporal degeneration (FTD), a progressive process marked by atrophy of the frontal and temporal lobes. FTD is one of the most common causes of dementia in people under the age of 65.

Principal investigator Mohammad Moshahid Khan, PhD, associate professor in the Department of Neurology, and co-investigator Tayebeh Pourmotabbed, PhD, professor in the Department of Microbiology, Immunology, and Biochemistry, are working on a project to find the first therapeutic intervention to prevent frontotemporal dementia or slow its progression in a mouse model linked with the condition.

The team is aiming to use a novel gene therapy called DNAzymes to target pathological tau aggregates, which cause frontotemporal dementia and its resulting cognitive impairment and progressive neuropathological symptoms. The team is examining the effective dose, frequency, and duration of treatment as well as its potential in reducing neurodegeneration and behavioral deficits in mice.

Our preliminary data suggest that DNAzyme is a novel therapeutic approach and has a great potential for preventing the accumulation of pathological tau. The results of this proposal would be foundational for future studies examining the clinical use of DNAzyme for other neurological diseases associated with traumatic brain injury and other tauopathies.”

Dr. Mohammad Moshahid Khan, PhD, associate professor in the Department of Neurology

“DNAzyme is a powerful gene therapy technique that can be used to prevent production of proteins associated with diseases, like tau protein in Alzheimer’s disease and dementia,” Dr. Pourmotabbed said. “We have used DNAzyme as a potential therapy for breast cancer, glioma, and Huntington’s disease in preclinical animal models with great success. Hopefully, with the use of DNAzyme technology, we would be able to reduce the risk of dementia after traumatic brain injury in veterans and other individuals that deal with this debilitating disease.”