Research Area: Human Disease

Ushering discoveries from bench to bedside

Studying cancer in the Sharp lab helped Courtney JnBaptiste learn strategic thinking skills that he uses as a patent agent, transforming technology into successful biotech businesses.

Raleigh McElvery | Department of Biology
October 17, 2021

Courtney JnBaptiste PhD ’16 spent the first 19 years of his life on the idyllic Caribbean island of Saint Lucia, surrounded by clear waters, sandy beaches, and a robust agricultural community. His family owned their own farm, where they grew bananas and other crops for export. JnBaptiste and his six siblings spent hours each day after school and on the weekends helping to harvest the fruits of their labor. “We were better off than most, but it was a hard existence,” he says. “I had to fight to make something out of life. Where I am today is a big leap.”

He has since moved to the U.S. and completed his PhD at the MIT Department of Biology. Today, he uses the strategic thinking skills he learned during graduate school in his job as a patent agent, helping researchers protect their inventions and start biotech companies.

Despite his exceptional grades, JnBaptiste didn’t enjoy school growing up, and he’d often try to convince his parents that he didn’t need to go to class. His mother, a middle school teacher, was unfazed by his excuses and sent him off to school most days. Despite his protests, JnBaptiste understood his mother’s motto that “education is the key to success.” He knew he’d need good academic standing and self-motivation to attain the financially-stable life he envisioned.

During high school, cable TV became available to his community for the first time, and he was overwhelmed by the deluge of information. He became hooked on Animal Planet and Discovery Channel, and decided that he wanted to be like Jeff Corwin, a biologist, wildlife conservationist, and TV personality. JnBaptiste knew he’d need a college education to reach his career aspirations, and — due to its proximity and promise of opportunity — the U.S. seemed like an ideal destination.

He was accepted to Bethune-Cookman University in Florida and declared a major in biology. He was awarded an environmental research grant, which allowed him to spend several semesters studying the snail populations in Blue Spring State Park. But a summer internship at the University of Kansas Medical Center was what ultimately convinced him to pursue molecular biology rather than environmental sciences. During his junior year, a new biochemistry professor arrived: Christopher Ainsley Davis, a former postdoc in the lab of Cathy Drennan at the MIT Department of Biology.

“When the two of us spoke, he said something that shocked me,” JnBaptiste recalls. “He told me, ‘You’re good enough for MIT and you should apply to their summer research program.’ That just blew my mind. I never thought I was of the MIT caliber — no one had ever challenged me like that before.”

At Davis’ urging, JnBaptiste applied to the MIT Summer Research Program in Biology (MSRP-Bio), and was placed in the lab of Nobel laureate Phil Sharp. In the 1970s, Sharp had co-discovered splicing, a molecular process that happens after DNA has been transcribed into RNA. Segments of the RNA strand are removed, and the remaining parts are stitched back together and translated into proteins that perform vital functions inside the cell.

Two people at a lab bench
JnBaptiste (left) completed his PhD research in the lab of Phil Sharp (right).

Under the supervision of graduate student and postdoc mentors, JnBaptiste spent the summer of 2009 investigating the role that RNA splicing plays in cancer. “It was the best time of my life,” he says. “I just I loved it. I loved the environment. I loved the lab. I loved MIT. And that experience had a profound impact on me.”

He enjoyed campus so much that he returned just one year later to begin his PhD. He was looking forward to returning to the lab bench, but what he didn’t anticipate was that his first semester of classes would be the most rigorous education he’d ever received. He excelled in biochemistry, but found 7.52 (Graduate Genetics) especially difficult. “It was the first time I’d ever failed an exam,” he recalls.

With the help of mentors, classmates, and tutors, JnBaptiste passed genetics and moved on to the stage of his PhD that he was most excited about: lab rotations. After testing out a few different research groups, he ultimately decided to return to the Sharp lab. In his own words: “It was home.”

JnBaptiste’s thesis project focused on a type of RNA known as microRNA (miRNA), which is never translated into a protein. Instead, it remains in its single-stranded RNA form and helps regulate gene expression. The Sharp lab found that removing all the miRNAs from adult cells prompted dramatic activation of embryonic genes. These genes are typically turned off in adult cells, and only expressed during early development when rapid cell division is required. But they can also be hijacked during cancer to create tumors.

JnBaptiste was surprised to find that adding the miRNAs back into the cells didn’t shut down these embryonic genes. In fact, restoring the miRNAs made the cells divide even more rapidly and increased their ability to form tumors — suggesting “global miRNA restoration” would not be a viable approach to treat cancer.

“This model that we developed showed miRNAs control a very important network in the context of both development and cancer,” JnBaptiste explains. “Cancer occurs when normal cellular processes go awry, so understanding those fundamental molecular interactions is critical to fighting the disease.”

By the time he graduated from MIT in 2016, JnBaptiste knew he enjoyed science, but didn’t have ambitions to run his own lab. Instead, he was curious about how lab experiments and research questions engender companies.

When he was still an MSRP-Bio student, JnBaptiste had met an intellectual property lawyer who’d come to speak on campus. He’d been saving her business card ever since, and reached out to her as his time at MIT was drawing to a close. With her assistance, JnBaptiste was offered a job as a scientific advisor at Goodwin Procter, the international law firm where she worked.

JnBaptiste has since transitioned to a similar role as a patent agent at Pabst Patent Group. There, he collaborates with lawyers to write patents protecting new research technology. While scientists are focused on the minutia of their day-to-day lab experiments, JnBaptiste is tasked with understanding the bigger picture, and how those experiments might lay the foundation for successful businesses that could revolutionize therapeutic approaches.

“As a grad student at MIT, I learned a lot about what it takes to be a strategic thinker in science,” JnBaptiste says. “People like my mentor, Phil Sharp, not only recognize a discovery, they look beyond it to envision its future potential as the next biotech company. That’s a skill I’m still honing as I work to develop my business acumen.”

Looking back at his career trajectory thus far, JnBaptiste is struck by the “beauty and diversity” that comes with earning a degree in biology. “Follow your passions,” he advises, “and surround yourself with people who can see the potential and value in you — even when you cannot yet see it yourself.”

Posted: 10.17.21
Top photo: Elisabeth Sherwin/Hello Headshots
Sara Prescott

Education

  • PhD, 2016, Stanford University School of Medicine
  • BA, 2008, Molecular Biology, Princeton University

Research Summary

Our bodies are tuned to detect and respond to cues from the outside world and from within through exquisite collaborations between cells. For example, the cells lining our airways communicate with sensory neurons in response to chemical and mechanical signals, and evoke key reflexes such as coughing. This cellular collaboration protects our airways from damage and stabilizes breathing, but can become dysregulated in disease. Despite their vital importance to human health, fundamental questions about how sensory transduction is accomplished at these sites remain unsolved. We use the mammalian airways as a model system to investigate how physiological insults are detected, encoded, and addressed at essential barrier tissues — with the ultimate goal of providing new ways to treat autonomic dysfunction.

Awards

  • Warren Alpert Distinguished Scholars Award, 2021
  • Life Sciences Research Foundation Fellowship, 2018
Probing pathogen spread during a global pandemic

Bailey Bowcutt investigated COVID-19 cases in rural Wyoming before coming to MIT for the summer and applying her knowledge to a new cellular invader.

Raleigh McElvery
July 23, 2021

The first time Bailey Bowcutt saw a lab it was nothing like she expected. Rather than a stark, sterile setting with sullen figures floating around like ghosts in white lab coats, the atmosphere was cordial and the dress casual. Some scientists even sported vibrant shirts with Marvel characters. A high school senior on a class field trip, Bowcutt couldn’t have predicted that the next time she’d set foot in the Wyoming Public Health Laboratory she’d no longer be a visitor, but a researcher performing diagnostic testing during a global pandemic. Now, as COVID-19 restrictions begin to lift, she’s taking the research tools she’s learned to Cambridge, Massachusetts to complete the Bernard S. and Sophie G. Gould MIT Summer Research Program in Biology (BSG-MSRP-Bio) and investigate how other types of pathogens spread.

Growing up in rural Wyoming, Bowcutt had little exposure to science because there were few research institutes close by. But watching family members suffer from gastrointestinal illness and other infections spurred her to pursue a degree in microbiology at Michigan State University (MSU). Shortly after she arrived on campus in the fall of 2019, she joined Shannon Manning’s lab studying antibiotic resistance in cattle.

Cows are prone to contracting a bacterial infection of the udder called mastitis. (In humans, a similar inflammation can occur in breast tissue.) Manning’s lab is looking at how antibiotic treatments affect the bovine gut microbiome and emergence of antibiotic resistance genes. Bowcutt’s role was to help identify these super bugs inside the cows’ gastrointestinal tracts.

“I got to go to the farm to take samples, which involved a glove that goes all the way up to the shoulder and some invasive maneuvers inside cows,” she explains. “Luckily, I was just the bag holder!”

Intimate sample collection aside, Bowcutt was excited about the work because it combined agriculture and human health research to solve issues plaguing rural communities. But her time on the farm was cut short when COVID-19 cases climbed in early 2020. She headed back to her home in Wyoming to begin remote MSU classes and, reminiscing about her field trip to the Wyoming Public Health Laboratory, reached out to the director to see if there were any internship opportunities.

“I’d barely learned how to do science at that point, but they needed people who could handle a pipette, so they took me,” she says. “I ended up being one of the first people there helping with COVID research, and I stayed for about a year-and-a-half while I took online classes.”

The lab would receive nasopharyngeal swabs from COVID-19 patients, and Bowcutt’s first task was to help extract RNA from the samples. Later, she transitioned to another project, which required performing PCR on untreated wastewater samples to glean a population-level understanding of where COVID-19 outbreaks were occurring.

She began toying with the idea of pursuing a PhD, but wasn’t sure what it would entail. So, in early 2021, she started Googling summer science programs and stumbled on BSG-MSRP-Bio. She was accepted, and paired with one of the very labs that had caught her eye online: assistant professor Becky Lamason’s group.

Microscopy image of parasites rocketing around inside cells
Listeria monocytogenes (yellow) rocket around their host cells (outlined in cyan) before ramming through the host’s membrane and that of its neighbor, forming a protrusion that is engulfed by the recipient cell. Image by Cassandra Vondrak.

“If you’ve ever seen microscopy pictures from the Lamason lab, they’re just so beautiful,” Bowcutt explains. Beautiful, yes — but she would soon learn these snapshots capture a chilling cellular invasion and molecular heist.

The Lamason lab watches malicious bacteria as they hijack molecules in human host cells to build long tails, rocket around, and punch through the cell membrane to spread. Bowcutt’s mentor, graduate student Yamilex Acevedo-Sánchez, focuses on the food-borne bacterium Listeria monocytogenes, which targets the gastrointestinal tract. Acevedo-Sánchez’s research aims to understand the host cell pathways that Listeria commandeers to move from one cell to the next in a process called cell-to-cell spread.

Together, Acevedo-Sánchez and Bowcutt are investigating several proteins in the human host cell involved in cellular transport and membrane remodeling (Caveolin-1, Pacsin2, and Fes), which could regulate Listeria’s spread. Over the summer, the duo has been adjusting the levels of these proteins and observing what happens to Listeria’s ability to move from cell-to-cell.

Bowcutt spends most of her days doing Western blots; growing Listeria and mammalian cells; and combining immunofluorescence assays with fixed and live cell microscopy to take her own striking microscopy images and movies of the parasites.

“I expected the work environment at MIT to be very intense, but everyone has been really friendly and willing to answer questions,” she says. “Some of my favorite experiences have just been in the lab while everyone is bustling around. It’s a welcome change after so much COVID-19 isolation.”

Now that the COVID-era occupancy restrictions have lifted, Bowcutt’s lab bench neighbor is Lamason herself. “She’s next to me doing experiments all the time,” Bowcutt explains, “which is cool because she’s really engaging with the research in the same way we are.”

Bowcutt says her summer experience has given her some much-needed practice designing research questions and devising the experiments to answer them. She’s also acquired a new skill she didn’t anticipate: interpreting ambiguous results and developing follow-up experiments to clarify them.

These days, the prospect of a PhD seems much less intimidating. In fact, the Lamason lab has done more than simply pique Bowcutt’s interested in fundamental biology research. She’s now considering ways to combine her microbiology skills with her interest in rural health care.

“I didn’t expect to see this much growth in myself,” she says, “and I know it’s making me a better scientist. I’m excited to return to MSU in the fall because I feel like I can do so much more now — and I would totally do it again.”

Hernandez Moura Silva

Education

  • PhD, 2011, University of São Paulo Heart Institute
  • MSc, Molecular Biology, 2008, University of Brasilia
  • BS, 2005, Biology, University of Brasilia

Research Summary

By utilizing an innovative and intersectional approach, our lab main goal is to reveal fundamental immune-related pathways that modulate organ and tissue physiology. Our work will help to develop new strategies to tune these molecular pathways in health and disease, leading to the development of much-needed therapeutic approaches for human diseases.

Awards

  • CAPES Thesis Award – Brazil, 2012
Lessons from teaching about the pandemic in real-time

Covid-19 class taps experts to help students and the public avoid misinformation as the crisis evolves.

Raleigh McElvery | Department of Biology
May 21, 2021

Just a few months after the Covid-19 pandemic took hold, Alan Grossman was already mulling over an idea for a new class to help people make sense of the virus. As head of MIT’s Department of Biology, he was aware of the key role fundamental research would play in the coming months. From RNA viruses and genomic sequencing to antibodies and vaccines, MIT students and the general public would need reliable scientific information to understand the evolving situation — and discern fact from fiction.

Not long after, the thoughts he’d feverishly scribbled on paper scraps scattered around his house began to take shape. With the support of the MIT School of Science, Accessibility Office, MIT Video Productions, and others around the institute, the Department of Biology added a new fall subject to the course catalog: 7.00 (Covid-19, SARS-CoV-2 and the Pandemic). Undergraduates could take the class for credit, as notable researchers stepped up to the virtual podium to share their expertise in front of a public livestream.

Grossman brought his nascent plans to associate department head and Whitehead Institute for Biomedical Research Member Peter Reddien, and together the two brainstormed individuals who might be willing to lead the class and queue speakers. They reached out to professor of biology and Whitehead Institute Member Richard Young, who served as an advisor to the World Health Organization and National Institutes of Health when a different virus of unknown origins was spreading — HIV. Young was also quick to mount a collaborative research campaign against SARS-CoV-2, the virus that causes Covid-19.

“I give Alan a lot of credit,” Young says. “He thought that it was the responsibility of the department to take the lead in filling the Covid-19 knowledge niche, and asked me if I would take this on and find a partner.”

Young contacted Ragon Institute Associate Director Facundo Batista, a world-class expert in immunology and infectious disease. Batista recalls being hesitant at first to co-lead the class; he couldn’t fathom condensing the global emergency into a single course. “But then I realized that the onslaught of information was the very reason we needed to organize this class — to help students and the public avoid misinformation,” he says. “We were filling a gap that the whole world was experiencing.”

Together, Batista and Young generated a list of 14 experts in an array of pandemic-related areas, including Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, David Baltimore of Caltech, and Kizzmekia Corbett of the National Institutes of Health. Each geared their lecture toward MIT undergraduates with a minimal biology background, and defined key terms and concepts so non-biologists watching the livestream could follow along as well.

Although Batista and Young agree that remote learning pales in comparison to in-person classes, the livestream format opened the talks up to thousands more viewers, and allowed the speakers to present their work without the need for travel. The recordings of each Tuesday lecture were posted on the Department of Biology’s website shortly thereafter, permitting asynchronous viewing for people around the world. The livestream audience regularly exceeded 1,000, and the YouTube views for each recording ranged from 4,000-97,000 and climbing. In many cases, the week’s topic fortuitously coincided with current events. For instance, Corbett spoke about vaccine development just days after the results of Pfizer-BioNTech’s first clinical trial were announced. As one of the NIH scientists who collaborated with Moderna to design another important mRNA-based vaccine, Corbett was able to discuss her reaction to the news and her expectations for Moderna’s imminent clinical trial results.

In addition to the livestream audience, each week roughly 300 MIT undergraduates would enter the Zoom room and get the opportunity to ask questions during the Q&A. Participation was unusually high, Young and Batista recall, thanks to the recitation sessions led by graduate student and teaching assistant Lena Afeyan. Afeyan would walk the students through the fundamentals of molecular biology, virology, and any other topics slated to feature heavily in the upcoming lecture. She also invited trainees and medical residents from various institutions to attend, in order to introduce students to the next generation of scientists and health-care professionals. The supplementary reading materials from these sessions are still available online, so biology teachers and other members of the public can access them.

“When I heard that this class was being put together, I hoped I could help make the content more accessible for the students and anyone else joining us,” Afeyan says. “The responses we got were overwhelming. It was incredible to hear from so many teachers, researchers, and alums across the world who watched the course every week.”

Even today, Afeyan, Young, and Batista continue to receive international kudos from scientists and non-scientists alike. At one point, Young was even interviewed by a radio station in Tasmania about the course.

“I learned a lot from 7.00 — not only about Covid-19, but about immunology and biology in general,” says Lucas Marden, a first-year undergraduate who enrolled in the class. “I particularly enjoyed the focus on the real-world response to the pandemic. We learned about everything from designing and developing different tests, treatments, and vaccines, to the scale-up of these technologies. The scientific community’s response to Covid-19 has been incredibly impressive, and I loved learning about it from the people at the forefront of their fields.”

Now, Grossman says, the department is planning to offer the class again this coming fall. “The initial idea stemmed from the need to share clear and reliable information about the pandemic as it began spreading,” he explains. “Although we’ve been living with Covid-19 for over a year now, that need is still present today — perhaps more so as we continue to learn what it will take to tame the virus.”

The next iteration of 7.00 will begin in September, and likely feature some of the same speakers and topics, along with new experts in areas that have recently emerged, such as the evolving viral variants. By arming the MIT community and the public with information from leading experts, Grossman, Batista, Young, and Afeyan hope to help the world navigate this pandemic — and prevent the next one.

Childhood hobbies jump-start a research career

MIT Biology junior Eduardo Canto tinkered with science long before he started studying Treacher Collins syndrome in the Calo lab.

Saima Sidik | Department of Biology
May 19, 2021

In seventh grade, Eduardo Canto wanted a dog. His mom said no, though. She didn’t want to spend her days vacuuming fur. They reached a compromise: Canto was allowed to have pet fish. Soon Canto’s disappointment with his new pets turned to curiosity. While he couldn’t train the fish to sit or roll over, he decided that breeding the fish could be a fun pastime.

An internet search told Canto that some aquarists use dried Indian almond leaves, a traditional Asian herbal remedy, to stimulate fish breeding, although no one is quite sure how the leaves do this. However, finding Indian almond leaves presented a problem for a kid without an Amazon account living far from the tree’s native habitat. On a whim, Canto picked up some similar-looking leaves in a park near his house in Puerto Rico. He knew they weren’t from an Indian almond tree, but he put them in the tank anyhow, just to see what would happen. A few days later, he noticed a collection of eggs attached to the bottom of a leaf!

Canto often took on little experiments like this, which caused his grandfather to predict early on that he would have a scientific career. Eight years after the breeding endeavor, Canto is fulfilling his grandfather’s prediction by studying Course 7 (Biology) at MIT, where he’s currently in his third year of a bachelor’s degree. Once again, fish have come into Canto’s life — he’s working in Eliezer Calo’s lab, where researchers use zebrafish to study a genetic disorder called Treacher Collins syndrome, which causes deformities in eyes, ears, cheekbones, and chins.

Throughout middle school and high school, Canto dipped his toes into many scientific disciplines. School science fairs motivated him to build a dry ice-powered trolley, a solar-powered water heater, and start a vegetable garden.

Sometimes, he admits, his motivation for joining science clubs wasn’t lofty. “I joined the math club because I got to miss a day of school every year for their annual competition,” he says with a laugh. But he also talks excitedly about his early experiments, particularly in biology. “I’ve always loved working with my hands,” he says.

Canto’s father, a medical doctor, encouraged his son’s interest by letting Canto shadow him at work. He also started a molecular biology summer program at Canto’s high school that taught students how to pipette and do simple experiments. By the time Canto applied to college, he was convinced he wanted to study biology, and MIT drew his attention because of its reputation as a top science school with excellent biology teachers. He knew it was the right choice for him when he attended Campus Preview Weekend, and found a large Puerto Rican community ready to welcome him. Even far from the island, he felt at home.

Canto has kept up with his roots since joining MIT by playing on a soccer team for Puerto Rican students. He’s also become part of a new community in a lab run by Eliezer Calo — who is a Puerto Rican himself. The lab is interested in ribosomes, the molecular machines that build proteins. Treacher Collins syndrome arises when cells can’t make ribosomes properly, and Canto wants to understand why that is.

Before Canto joined the Calo lab, the group had already started studying a protein called DDX21 that’s involved in making ribosomes in both humans and zebrafish. When genetic mutations in zebrafish cause DDX21 to go to the wrong part of the cell, the fish develop jaw deformations that mirror Treacher Collins syndrome. The Calo lab thinks cells with mislocalized DDX21 probably don’t produce ribosomes as well as normal cells, but they’re still testing this hypothesis.

Canto wants to probe the relationship between DDX21 and Treacher Collins syndrome further, but fish reproduce slowly, so they’re not ideal organisms for his research. Instead, he’s built a strain of Escherichia coli bacteria that carry DDX21 in place of the equivalent bacterial gene. DDX21 helps these bacteria survive the stress associated with cold temperatures, so without it, the bacteria will die in the cold. Canto hopes to take advantage of this trait by finding small molecules that stop the bacteria from growing at low temperatures — just like a DDX21 mutation would. Studying how these molecules bind DDX21 will help him understand which parts of this protein are important for its function.

The possibility that this work will one day reveal how Treacher Collins syndrome develops in patients is rewarding to Canto, and in fact he hopes helping patients will soon become his life’s focus. He wants to attend medical school, and eventually become a doctor. The human physiology class he took last semester was one of his favorites, even though it was over Zoom due to the COVID-19 pandemic. Becoming a doctor will let him help others while studying topics he finds fascinating. “Medicine is like biology on steroids!” he says.

And who knows — one day after he’s a doctor, maybe he’ll even get that pet he’s always wanted. But unlike Canto’s interest in biology, some of his interests have evolved over time. These days, he prefers cats over dogs.

Photo credit: Saima Sidik
Posted: 5.19.21
Olivia Corradin

Education

  • PhD, 2015, Case Western Reserve University
  • BS, 2010, Biochemistry, Marquette University

Research Summary

Our lab studies genetic and epigenetic variation that contributes to human disease by disrupting gene expression programs. We utilize biological insights into the mechanisms of gene regulation in order to determine the impact of disease-associated variants on cellular function. We aim to identify actionable insights into disease pathogenesis by studying the confluence of genetic and epigenetic risk factors of human diseases, including multiple sclerosis and opioid use disorder.

Awards

  • NIH Director’s Pioneer Award Program Avenir Award, 2017
Spying on enzymes while they perform chemical reactions could help treat gut ailments
Raleigh McElvery
March 26, 2021

Humans breathe oxygen, but many microbes deep within in our gut don’t have access to this precious resource. Instead, they breathe sulfur compounds, releasing hydrogen sulfide in the process. This colorless gas is best-known for its rotten stench, but inside the human colon it has been linked to a thinner mucus barrier, and ailments such as inflammatory bowel disease, Crohn’s disease, ulcerative colitis, and colorectal cancer. In order to develop potential treatments, researchers are probing how microbes create hydrogen sulfide and which molecules they use.

To help further these efforts, Catherine Drennan’s lab and Heather Kulik’s lab at MIT collaborated with Emily Balskus’ lab at Harvard University to investigate the structure and mechanism of an enzyme that’s critical for hydrogen sulfide production: isethionate sulfite-lyase (IslA). The team examined IslA while it was bound to a metabolite that’s readily available in the gut — and revealed how the bacterium Bilophila wadsworthia uses this interaction to help generate the hydrogen sulfide precursor called sulfite. The researchers then compared IslA’s binding behavior to other enzymes in the same family, in order to better understand how these enzymes have evolved to perform challenging chemistry on a wide variety of molecules. Their findings were published on Mar. 26 in the journal Cell Chemical Biology.

“Although abundant, sulfide-producing bacteria are not well understood,” says Drennan, a professor of biology and chemistry and a Howard Hughes Medical Institute investigator. “By characterizing the enzymes in these bacteria that are responsible for sulfur metabolism, we can develop therapeutic strategies to limit production of hydrogen sulfide that can lead to disease.”

Although researchers have been studying bacterial sulfur respiration for decades, IslA was only recently identified. This enzyme breaks the bond between a carbon atom and a sulfur atom in a compound called isethionate, which is a prevalent metabolite in the human body. In doing so, IslA releases the sulfite that bacteria such as B. wadsworthia use to produce hydrogen sulfide.

IslA is a member of a large family of enzymes, known as glycyl radical enzyme (GREs). Scientists can learn a lot from examining the way GREs bind to other molecules, according to Christopher Dawson PhD ’20, the study’s co-first author.

GREs contain a binding site (or “active site”) where they latch onto their respective substrates to perform chemical reactions. “Understanding GREs better will aid in drug design efforts to combat the deleterious effects of some of these enzymes,” Dawson says. “It will also help to engineer enzymes that perform diverse, challenging reactions to expand the toolkit for chemical synthesis.”

To this end, Dawson wanted to compare IslA’s active site — where it binds to isethionate to break the C-S bond — to other enzymes in the GRE family. He used X-ray crystallography to visualize this interaction at the level of individual atoms. The GREs he examined shared similar “barrel-like” structures in their active sites, but used these core features in different ways, depending on the substrates they bound. For instance, isethionate bound higher in IslA’s active site compared to the way other GREs bind their respective substrates. While this aberrant binding behavior is quite unique — even among GREs — another group had found something similar when they elucidated IslA’s structure in a different bacterium. And, the Drennan lab suspects this pattern could be prevalent in other classes of enzymes as well.

Next, Dawson and his colleagues wanted to investigate how IslA goes about cleaving the C-S bond once the enzyme has bound to isethionate. Others had predicted this process would occur via a “migration” reaction. In that scenario, the sulfite leaving group first migrates to another carbon atom and then that C-S bond is cleaved to release it. However, after co-first author Stephania Irwin generated multiple IslA variants, the Kulik lab performed computational analyses, and the researchers completed structural comparisons, the team concluded that migration was not occurring. Instead, IslA appeared to be performing an “elimination” reaction that severed the C-S bond without forming another one via migration.

Now that they know more about IslA — and GREs in general — the researchers hope their insights will aid drug design.

“Understanding how pathogens use enzymes like these to extract sulfite from their hosts and fuel hydrogen sulfide production has very clear therapeutic implications,” Dawson says. “And that’s one of the things I like best about this story.”

Citation
“Molecular Basis of C-S Bond Cleavage in the Glycyl Radical Enzyme Isethionate Sulfite-Lyase”
Cell Chemical Biology, online March 26, 2021,
DOI: 10.1016/j.chembiol.2021.03.001
Christopher D. Dawson, Stephania M. Irwin, Lindsey R. F. Backman, Chip Le, Jennifer X. Wang, Vyshnavi Vennelakanti, Zhongyue Yang, Heather J. Kulik, Catherine L. Drennan, and Emily P. Balskus

Understanding antibodies to avoid pandemics

Structural biologist Pamela Björkman shared insights into pandemic viruses as part of the Department of Biology’s IAP seminar series.

Saima Sidik | Department of Biology
January 19, 2021

Last month, the world welcomed the rollout of vaccines that may finally curb the Covid-19 pandemic. Pamela Björkman, the David Baltimore Professor of Biology and Bioengineering at Caltech, wants to understand how antibodies like the ones elicited by these vaccines target the SARS-CoV-2 virus that causes Covid-19. She hopes this understanding will guide treatment strategies and help design vaccines against future pandemics. She shared her lab’s work during the MIT Department of Biology’s Independent Activities Period (IAP) seminar series, Immunity from Principles to Practice, on Jan. 12.

“Pamela is an amazing scientist, a strong advocate for women in science, and has a stellar history of studying the structural biology of virus-antibody interactions,” says Whitehead Institute for Biomedical Research Member Pulin Li, the Eugene Bell Career Development Professor of Tissue Engineering and one of the organizers of this year’s lecture series.

Immunology research often progresses from the lab bench to the clinic quickly, as was the case with Covid-19 vaccines, says Latham Family Career Development Professor of Biology and Whitehead Institute Member Sebastian Lourido, who organized the lecture series with Li. He and Li chose to focus this year’s seminar series on immunity because this field highlights the tie between basic molecular biology, which is a cornerstone of the Department of Biology, and practical applications.

“Pamela’s work is an excellent example of how fundamental discoveries can be intimately tied to real-world applications,” Lourido says.

Björkman’s lab has a long history of studying antibodies, which are protective proteins that the body generates in response to invading pathogens. Björkman focuses on neutralizing antibodies, which bind and jam up the molecular machines that let viruses reproduce in human cells. Last fall, the U.S. Food and Drug Administration (FDA) authorized a combination of two neutralizing antibodies, produced by the pharmaceutical company Regeneron, for emergency use in people with mild to moderate Covid-19. This remains one of the few treatments available for the disease.

Together with Michel Nussenzweig’s lab at The Rockefeller University, Börkman’s lab identified four categories of neutralizing antibodies that prevent a protein that decorates SARS-CoV-2’s surface, called the spike protein, from binding to a human protein called ACE2. Spike acts like the virus’s key, with ACE2 being the lock it has to open to enter human cells. Some of the antibodies that Björkman’s lab characterized bind to the tip of spike so that it can’t fit into ACE2, like sticking a wad of chewing gum on top of the virus’s key. Others block spike proteins from interacting with ACE2 by preventing them from altering their orientations. Understanding the variety of ways that neutralizing antibodies work will let scientists figure out how to combine them into maximally effective treatments.

Björkman isn’t satisfied with just designing treatments for this pandemic, however. “Coronavirus experts say this is going to keep happening,” she says. “We need to be prepared next time.”

To this end, Björkman’s lab has put pieces of spike-like proteins from multiple animal coronaviruses onto nanoparticles and injected them into mice. This made the mice generate antibodies against a mix of pathogens that are poised to jump into humans, suggesting that scientists could use this approach to create vaccines before pandemics occur. Importantly, the nanoparticles still work after they’re freeze-dried, meaning that companies could stockpile them, and that they could be shipped at room temperature.

Björkman’s talk was the second in the Immunity from Principles to Practice series, which was kicked off by Gabriel Victora from The Rockefeller University. Victora discussed how antibodies are produced in structures called germinal centers that are found in lymph nodes and the spleen.

Next in the series is Chris Garcia from Stanford University, who will speak on Jan. 19 about his lab’s work on engineering immune signaling molecules to maximize their potential to elicit therapeutic responses. To round out the series, Yasmine Belkaid from the National Institute of Allergy and Infectious Disease will speak on Jan. 26 about interactions between the gut microbiome and the pathogens we ingest. These talks complement a number of career development seminars that were organized by graduate students Fiona Aguilar, Alex Chan, Chris Giuliano, Alice Herneisen, Jimmy Ly, and Aditya Nair.

3 Questions: Phillip Sharp on the discoveries that enabled RNA vaccines for Covid-19

Curiosity-driven basic science in the 1970s laid the groundwork for today’s leading vaccines against the novel coronavirus.

School of Science
December 11, 2020

Some of the most promising vaccines developed to combat Covid-19 rely on messenger RNA (mRNA) — a template cells use to carry genetic instructions for producing proteins. The mRNA vaccines take advantage of this cellular process to make proteins that then trigger an immune response that targets SARS-CoV-2, the virus that causes Covid-19.

Compared to other types of vaccines, recently developed technologies allow mRNA vaccines to be rapidly created and deployed on a large-scale — crucial aspects in the fight against Covid-19. Within the year since the identification and sequencing of the SARS-CoV-2 virus, companies such as Pfizer and Moderna have developed mRNA vaccines and run large-scale trials in the race to have a vaccine approved by the U.S. Food and Drug Administration — a feat unheard of with traditional vaccines using live attenuated or inactive viruses. These vaccines appear to have a greater than 90 percent efficacy in protecting against infection.

The fact that these vaccines could be rapidly developed within these last 10 months rests on more than four decades of study of mRNA. This success story begins with Institute Professor Phillip A. Sharp’s discovery of split genes and spliced RNA that took place at MIT in the 1970s — a discovery that would earn him the 1993 Nobel Prize in Physiology or Medicine.

Sharp, a professor within the Department of Biology and member of the Koch Institute for Integrative Cancer Research at MIT, commented on the long arc of scientific research that has led to this groundbreaking, rapid vaccine development — and looked ahead to what the future might hold for mRNA technology.

Q: Professor Sharp, take us back to the fifth floor of the MIT Center for Cancer Research in the 1970s. Were you and your colleagues thinking about vaccines when you studied viruses that caused cancer?

A: Not RNA vaccines! There was a hope in the ’70s that viruses were the cause of many cancers and could possibly be treated by conventional vaccination with inactivated virus. This is not the case, except for a few cancers such as HPV causing cervical cancer.

Also, not all groups at the MIT Center for Cancer Research (CCR) focused directly on cancer. We knew so little about the causes of cancer that Professor Salvador Luria, director of the CCR, recruited faculty to study cells and cancer at the most fundamental level. The center’s three focuses were virus and genetics, cell biology, and immunology. These were great choices.

Our research was initially funded by the American Cancer Society, and we later received federal funding from the National Cancer Institute, part of the National Institutes of Health and the National Science Foundation — as well as support from MIT through the CCR, of course.

At Cold Spring Harbor Laboratory in collaboration with colleagues, we had mapped the parts of the adenovirus genome responsible for tumor development. While doing so, I became intrigued by the report that adenovirus RNA in the nucleus was longer than the RNA found outside the nucleus in the cytoplasm where the messenger RNA was being translated into proteins. Other scientists had also described longer-than-expected nuclear RNA from cellular genes, and this seemed to be a fundamental puzzle to solve.

Susan Berget, a postdoc in my lab, and Claire Moore, a technician who ran MIT’s electron microscopy facility for the cancer center and would later be a postdoc in my lab, were instrumental in designing the experiments that would lead to the iconic electron micrograph that was the key to unlocking the mystery of this “heterogeneous” nuclear RNA. Since those days, Sue and Claire have had successful careers as professors at Baylor College of Medicine and Tufts Medical School, respectively.

The micrograph showed loops that would later be called “introns” — unnecessary extra material in between the relevant segments of mRNA, or “exons.” These exons would be joined together, or spliced, to create the final, shorter message for the translation to proteins in the cytoplasm of the cell.

This data was first presented at the Cancer Center fifth floor group meeting that included Bob Weinberg, David Baltimore, David Housman, and Nancy Hopkins. Their comments, particularly those of David Baltimore, were catalysts in our discovery. Our curiosity to understand this basic cellular mechanism drove us to learn more, to design the experiments that could elucidate the RNA splicing process. The collaborative environment of the MIT Cancer Center allowed us to share ideas and push each other to see problems in a new way.

Q: Your discovery of RNA splicing was a turning point, opening up new avenues that led to new applications. What did this foundation allow you to do that you couldn’t do before?

A: Our discovery in 1977 occurred just as biotechnology appeared with the objective of introducing complex human proteins as therapeutic agents, for example interferons and antibodies. Engineering genes to express these proteins in industrial tanks was dependent on this discovery of gene structure. The same is true of the RNA vaccines for Covid-19: By harnessing new technology for synthesis of RNA, researchers have developed vaccines whose chemical structure mimics that of cytoplasmic mRNA.

In the early 1980s, following isolation of many human mutant disease genes, we recognized that about one-fifth of these were defective for accurate RNA splicing. Further, we also found that different isoforms of mRNAs encoding different proteins can be generated from a single gene. This is “alternative RNA splicing” and may explain the puzzle that humans have fewer genes — 21,000 to 23,000 — than many less complex organisms, but these genes are expressed in more complex protein isoforms. This is just speculation, but there are so many things about biology yet to be discovered.

I liken RNA splicing to discovering the Rosetta Stone. We understood how the same letters of the alphabet could be written and rewritten to form new words, new meaning, and new languages. The new “language” of mRNA vaccines can be developed in a laboratory using a DNA template and readily available materials. Knowing the genetic code of the SARS-CoV-2 is the first step in generating the mRNA vaccine. The effective delivery of vaccines into the body based on our fundamental understanding of mRNA took decades more work and ingenuity to figure out how to evade other cellular mechanisms perfected over hundreds of millions of years of evolution to destroy foreign genetic material.

Q: Looking ahead 40 more years, where do you think mRNA technology might be?

A: In the future, mRNA vaccine technology may allow for one vaccine to target multiple diseases. We could also create personalized vaccines based on individuals’ genomes.

Messenger RNA vaccines have several benefits compared to other types of vaccines, including the use of noninfectious elements and shorter manufacturing times. The process can scaled up, making vaccine development faster than traditional methods. RNA vaccines can also be moved rapidly into clinical trials, which is critical for the next pandemic.

It is impossible to predict the future of RNA therapies, such as the new vaccines, but there are some signs that new advancements could happen very quickly. A few years ago, the first RNA-based therapy was approved for treatment of lethal genetic disease. This treatment was designed through the discovery of RNA interference. Messenger RNA-based therapies will also likely be used to treat genetic diseases, vaccinate against cancer, and generate transplantable organs. It is another tool at the forefront of modern medical care.

But keep in mind that all mRNAs in human cells are encoded by only 2 percent of the total genome sequence. Most of the other 98 percent is transcribed into cellular RNAs whose activities remain to be discovered. There could be many future RNA-based therapies.