The Women of RNA: Two Award-Winners Share Why They Spent Their Careers Studying DNA's Lesser-Known Cousin
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
Joan Steitz (left) and Lynne Maquat (right) were honored with the Wolf Prize in Medicine and the Warren Alpert Foundation Prizer this year for their fundamental work on RNA.
When Lynne Maquat, who leads the Center for RNA Biology at the University of Rochester, became interested in the ribonucleic acid molecule in the 1970s, she was definitely in the minority. The same was true for Joan Steitz, now professor of molecular biophysics and biochemistry at Yale University, who began to study RNA a decade earlier in the 1960s.
"My first RNA experiment was a failure, because we didn't understand how things worked," Steitz recalls. In her first undergraduate experiment, she unwittingly used a lab preparation that destroyed the RNA. "Unknowingly, our preparation contained enzymes that degraded our RNA."
At the time, scientists pursuing genetic research tended to focus on DNA, or deoxyribonucleic acid — and for good reason. It was clear that the enigmatic double-helix ribbon held the answers to organisms' heredity, genetic traits, development, growth and aging. If scientists could decipher the secrets of DNA and understand how its genetic instructions translate into the body's functions in health and disease, they could develop treatments for all kinds of diseases. On the contrary, the prevailing dogma of the time viewed RNA as merely a helper that passively carried out DNA's genetic instructions for protein-making — so it received much less attention.
But Maquat and Steitz weren't interested in heredity. They studied biochemistry and biophysics, so they wanted to understand how RNA functioned on the molecular level — how it carried instructions, catalyzed reactions, and helped build protein bonds, among other things.
"I'm a mechanistic biochemist, so I like to know how things happen," Maquat says. "Once you understand the mechanism, you can think of how to solve problems." And so the quest to understand how RNA does its job became the focus of both women's careers.
"People can now appreciate why some of us studied RNA for such a long time."
Half a century later, in 2021, their RNA work has earned two prestigious recognitions only months from each other. In February, they received the Wolf Prize in Medicine, followed by the Warren Alpert Foundation Prize in May, awarded to scientists whose achievements led to prevention, cure or treatments of human diseases.
It was the development of the COVID-19 vaccines that made RNA a household name. Made by Moderna and Pfizer, the vaccines use the RNA molecule to deliver genetic instructions for making SARS-CoV-2's characteristic spike protein in our cells. The presence of this foreign-looking protein triggers the immune system to attack and remember the pathogen. As the vaccines reached the finish line, RNA took center stage, and it was Maquat's and Steitz's research that helped reveal how these molecular cogwheels drive many biological functions within cells.
If you think of a cell as a kingdom, the DNA plays the role of a queen. Like a monarch in a palace, DNA nestles inside the cell's nucleus issuing instructions needed for the cell to function. But no queen can successfully govern without her court, her messengers, and her soldiers, as well as other players that make her kingdom work. That's what RNAs do — they act as the DNA's vassals. They carry instructions for protein assembly, catalyze reactions and supervise many other processes to make sure the cellular kingdom performs as it should.
There are a myriad of these RNA vassals in our cells, and each type has its own specific task. There are messenger RNAs that deliver genetic instructions for protein synthesis from DNA to ribosomes, the cells' protein-making factories. There are ribosomal RNAs that help stitch together amino acids to make proteins. There are transfer RNAs that can bring amino acids to this protein synthesis machine, keeping it going. Then there are circular RNAs that act as sponges, absorbing proteins to help regulate the activity of genes. And that's only the tip of the iceberg when it comes to RNA diversity, researchers say.
"We know what the most abundant and important RNAs are doing," says Steitz. "But there are thousands of different ones, and we still don't have a full knowledge of them."
Critical to RNA's proper functioning is a process called splicing, in which a precursor mRNA is transformed into mature, fully-functional mRNA — a phenomenon that Steitz's work helped elucidate. The splicing process, which takes place in cellular assembly lines, involves removing extra RNA sequences and stringing the remaining RNA pieces together. Steitz found that tiny RNA particles called snRNPs are crucial to this process. They act as handy helpers, finding and removing errant genetic material from the mRNA molecules.
A dysfunctional RNA assembly line leads to diseases, including many cancers. For instance, Steitz found that people with Lupus — an autoimmune disorder — have antibodies that mistakenly attack the little snRNP helpers. She also discovered that when snRNPs don't do their job properly, they can cause what scientists call mis-splicing, producing defective mRNAs.
Fortunately, cells have a built-in quality-control process that can spot and correct these mistakes, which is what Maquat studied in her work. In 1981, she discovered a molecular quality-control system that spots and destroys such incorrectly assembled mRNA. With the cryptic name "nonsense-mediated mRNA decay" or NMD, this process is vital to the health and wellbeing of a cellular kingdom in humans — because splicing mistakes happen far more often than one would imagine.
"We estimate that about a third of our mRNA are mistakes," Maquat says. "And nonsense-mediated mRNA decay cleans up these mistakes." When this quality-control system malfunctions, defective mRNA forge faulty proteins, which mess up the cellular machinery and cause disease, including various forms of cancer.
Scientists' newfound appreciation of RNA opens door to many novel treatments.
Now that the first RNA-based shots were approved, the same principle can be used for create vaccines for other diseases, the two RNA researchers say. Moreover, the molecule has an even greater potential — it can serve as a therapeutic target for other disorders. For example, Spinraza, a groundbreaking drug approved in 2016 for spinal muscular atrophy, uses small snippets of synthetic genetic material that bind to the RNA, helping fix splicing errors. "People can now appreciate why some of us studied RNA for such a long time," says Maquat.
Steitz is thrilled that the entire field of RNA research is enjoying the limelight. "I'm delighted because the prize is more of a recognition of the field than just our work," she says. "This is a more general acknowledgment of how basic research can have a remarkable impact on human health."
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.
Catching colds may help protect kids from Covid
A new study shows that the immune system's response to colds can help prepare it to defend against COVID-19 - but only in the very young.
A common cold virus causes the immune system to produce T cells that also provide protection against SARS-CoV-2, according to new research. The study, published last month in PNAS, shows that this effect is most pronounced in young children. The finding may help explain why most young people who have been exposed to the cold-causing coronavirus have not developed serious cases of COVID-19.
One curiosity stood out in the early days of the COVID-19 pandemic – why were so few kids getting sick. Generally young children and the elderly are the most vulnerable to disease outbreaks, particularly viral infections, either because their immune systems are not fully developed or they are starting to fail.
But solid information on the new infection was so scarce that many public health officials acted on the precautionary principle, assumed a worst-case scenario, and applied the broadest, most restrictive policies to all people to try to contain the coronavirus SARS-CoV-2.
One early thought was that lockdowns worked and kids (ages 6 months to 17 years) simply were not being exposed to the virus. So it was a shock when data started to come in showing that well over half of them carried antibodies to the virus, indicating exposure without getting sick. That trend grew over time and the latest tracking data from the CDC shows that 96.3 percent of kids in the U.S. now carry those antibodies.
Antibodies are relatively quick and easy to measure, but some scientists are exploring whether the reactions of T cells could serve as a more useful measure of immune protection.
But that couldn't be the whole story because antibody protection fades, sometimes as early as a month after exposure and usually within a year. Additionally, SARS-CoV-2 has been spewing out waves of different variants that were more resistant to antibodies generated by their predecessors. The resistance was so significant that over time the FDA withdrew its emergency use authorization for a handful of monoclonal antibodies with earlier approval to treat the infection because they no longer worked.
Antibodies got most of the attention early on because they are part of the first line response of the immune system. Antibodies can bind to viruses and neutralize them, preventing infection. They are relatively quick and easy to measure and even manufacture, but as SARS-CoV-2 showed us, often viruses can quickly evolve to become more resistant to them. Some scientists are exploring whether the reactions of T cells could serve as a more useful measure of immune protection.
Kids, colds and T cells
T cells are part of the immune system that deals with cells once they have become infected. But working with T cells is much more difficult, takes longer, and is more expensive than working with antibodies. So studies often lags behind on this part of the immune system.
A group of researchers led by Annika Karlsson at the Karolinska Institute in Sweden focuses on T cells targeting virus-infected cells and, unsurprisingly, saw that they can play a role in SARS-CoV-2 infection. Other labs have shown that vaccination and natural exposure to the virus generates different patterns of T cell responses.
The Swedes also looked at another member of the coronavirus family, OC43, which circulates widely and is one of several causes of the common cold. The molecular structure of OC43 is similar to its more deadly cousin SARS-CoV-2. Sometimes a T cell response to one virus can produce a cross-reactive response to a similar protein structure in another virus, meaning that T cells will identify and respond to the two viruses in much the same way. Karlsson looked to see if T cells for OC43 from a wide age range of patients were cross-reactive to SARS-CoV-2.
And that is what they found, as reported in the PNAS study last month; there was cross-reactive activity, but it depended on a person’s age. A subset of a certain type of T cells, called mCD4+,, that recognized various protein parts of the cold-causing virus, OC43, expressed on the surface of an infected cell – also recognized those same protein parts from SARS-CoV-2. The T cell response was lower than that generated by natural exposure to SARS-CoV-2, but it was functional and thus could help limit the severity of COVID-19.
“One of the most politicized aspects of our pandemic response was not accepting that children are so much less at risk for severe disease with COVID-19,” because usually young children are among the most vulnerable to pathogens, says Monica Gandhi, professor of medicine at the University of California San Francisco.
“The cross-reactivity peaked at age six when more than half the people tested have a cross-reactive immune response,” says Karlsson, though their sample is too small to say if this finding applies more broadly across the population. The vast majority of children as young as two years had OC43-specific mCD4+ T cell responses. In adulthood, the functionality of both the OC43-specific and the cross-reactive T cells wane significantly, especially with advanced age.
“Considering that the mortality rate in children is the lowest from ages five to nine, and higher in younger children, our results imply that cross-reactive mCD4+ T cells may have a role in the control of SARS-CoV-2 infection in children,” the authors wrote in their paper.
“One of the most politicized aspects of our pandemic response was not accepting that children are so much less at risk for severe disease with COVID-19,” because usually young children are among the most vulnerable to pathogens, says Monica Gandhi, professor of medicine at the University of California San Francisco and author of the book, Endemic: A Post-Pandemic Playbook, to be released by the Mayo Clinic Press this summer. The immune response of kids to SARS-CoV-2 stood our expectations on their head. “We just haven't seen this before, so knowing the mechanism of protection is really important.”
Why the T cell immune response can fade with age is largely unknown. With some viruses such as measles, a single vaccination or infection generates life-long protection. But respiratory tract infections, like SARS-CoV-2, cause a localized infection - specific to certain organs - and that response tends to be shorter lived than systemic infections that affect the entire body. Karlsson suspects the elderly might be exposed to these localized types of viruses less often. Also, frequent continued exposure to a virus that results in reactivation of the memory T cell pool might eventually result in “a kind of immunosenescence or immune exhaustion that is associated with aging,” Karlsson says. https://leaps.org/scientists-just-started-testing-a-new-class-of-drugs-to-slow-and-even-reverse-aging/particle-3 This fading protection is why older people need to be repeatedly vaccinated against SARS-CoV-2.
Policy implications
Following the numbers on COVID-19 infections and severity over the last three years have shown us that healthy young people without risk factors are not likely to develop serious disease. This latest study points to a mechanism that helps explain why. But the inertia of existing policies remains. How should we adjust policy recommendations based on what we know today?
The World Health Organization (WHO) updated their COVID-19 vaccination guidance on March 28. It calls for a focus on vaccinating and boosting those at risk for developing serious disease. The guidance basically shrugged its shoulders when it came to healthy children and young adults receiving vaccinations and boosters against COVID-19. It said the priority should be to administer the “traditional essential vaccines for children,” such as those that protect against measles, rubella, and mumps.
“As an immunologist and a mother, I think that catching a cold or two when you are a kid and otherwise healthy is not that bad for you. Children have a much lower risk of becoming severely ill with SARS-CoV-2,” says Karlsson. She has followed public health guidance in Sweden, which means that her young children have not been vaccinated, but being older, she has received the vaccine and boosters. Gandhi and her children have been vaccinated, but they do not plan on additional boosters.
The WHO got it right in “concentrating on what matters,” which is getting traditional childhood immunizations back on track after their dramatic decline over the last three years, says Gandhi. Nor is there a need for masking in schools, according to a study from the Catalonia region of Spain. It found “no difference in masking and spread in schools,” particularly since tracking data indicate that nearly all young people have been exposed to SARS-CoV-2.
Both researchers lament that public discussion has overemphasized the quickly fading antibody part of the immune response to SARS-CoV-2 compared with the more durable T cell component. They say developing an efficient measure of T cell response for doctors to use in the clinic would help to monitor immunity in people at risk for severe cases of COVID-19 compared with the current method of toting up potential risk factors.
In this week's Friday Five: The eyes are the windows to the soul - and biological aging?
Plus, what bean genes mean for health and the planet, a breathing practice that could lower levels of tau proteins in the brain, AI beats humans at assessing heart health, and the benefits of "nature prescriptions"
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on new scientific theories and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Here are the stories covered this week:
- The eyes are the windows to the soul - and biological aging?
- What bean genes mean for health and the planet
- This breathing practice could lower levels of tau proteins
- AI beats humans at assessing heart health
- Should you get a nature prescription?