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An early diagnosis sparks a lifelong interest in science and medicine

Senior Isha Mehrotra works to discover more about autoimmune diseases, aiming for a future in which patients can be treated effectively or avoid the conditions altogether.

Alli Armijo | MIT News correspondent

March 25, 2022

“Five second rule!” her classmates shouted as they rushed to pick up some food they had dropped on the ground. At that moment, 10-year-old Isha Mehrotra knew what she wanted to do for the annual science fair.

After scouring the internet with her father, Mehrotra learned how to culture bacteria from home, first tossing food on the floor of her kitchen and swabbing samples onto agar plates — her very first microbiology project. She remembers presenting the data to her peers, watching their faces fall as they realized how much bacteria was on the food even after just five seconds. The experience kindled Mehrotra’s love of learning about the natural world, and more importantly, sharing that knowledge with others.

Now a senior studying biology, Mehrotra enjoys the investigative quality of science above all else.

“The more you study science, the more you realize what you don’t know about it,” she says.

MIT has also been a place for Mehrotra to learn more about herself. In the spring of her sophomore year, she worked in the lab of Alessio Fasano with Maureen Leonard at Massachusetts General Hospital’s Mucosal Immunology and Biology Research Center, investigating the blood microbiome of pediatric patients with an autoimmune condition called celiac disease — which Mehrotra herself was diagnosed with when she was a child.

Her diagnosis sparked an early interest in science and medicine. Today, she works to discover more about celiac, its causes, and effects on the individuals who have it, aiming for a future in which patients can be treated effectively or avoid getting the disease altogether.

Through her research experience, which has included publishing her work as a first author in the journal Current Research in Microbial Sciences, Mehrotra has learned that when presenting her findings, having faith in her work is half the battle, especially when challenging canonical scientific beliefs. “At the end of the day, you know, your data is your data. And presenting that with conviction and confidence is something that I’ve learned how to balance. I try to do that even when I’m acknowledging that there are various aspects of the work that have yet to be understood or validated,” she says.

Mehrotra also serves as a member on the Board of Directors at Boston Children’s Hospital Celiac Kids Connection, where she works to build a safe space for children with celiac. She she understands firsthand the physical and emotional toll celiac disease can have, and values the opportunity to learn more about how to support people and navigate these challenges. For instance, she recognized the connection of food insecurity to celiac early on, as celiac is treated with a gluten-free diet. One of her most fulfilling projects, funded through the PKG Center at MIT, has been helping reduce gluten-free food insecurity exacerbated by the pandemic, working with a team at Children’s to research and mitigate these food access issues.

“It comes back to looking at things in different ways. How can I have a great impact in one area if I don’t consider all the various facets of it?” she asks.

In her classes, Mehrotra has also been drawn to complex public health topics with multiple perspectives, developing an anthropology background via her HASS coursework (for which she was named a Burchard Scholar) and an entrepreneurial framework by participating in MIT Sandbox. In January 2020, she took HST.434 (Evolution of an Epidemic), travelling to South Africa to study the evolution of the HIV/AIDS epidemic in the area. The experience was eye-opening for Mehrotra; she saw firsthand the variety of factors — social, political, biological — needed to approach a singular issue.

In June of last year, Mehrotra participated in the MIT Washington Summer Internship Program, where she worked for Gryphon Scientific, studying data to see how pandemics emerge and evolve at the biological level and what can be done at the policy level to prevent them. The experience allowed Mehrotra to see how different players can influence a singular problem.

“Social processes that underlie science and medicine are really important to me to continue studying,” she says.

On campus, Mehrotra has also been working as a mentor in her dormitory, Maseeh Hall, and peer tutor. During her first year she joined dynaMIT, a STEM outreach program for middle school students in Boston through which she taught biology in ways that made it more fun and accessible. She has also found ways to bring MIT biology students together as co-president of the Biology Undergraduate Sudent Assocation and to provide funding for on-campus initiatives as a board member of the Harvard-MIT Cooperative. Mehrotra also taught chemistry and biology to students in Wales through the Global Teaching Labs program and was a teaching assistant for the biology lab course 7.002 (Fundamentals of Experimental Molecular Biology) and for 7.012 (Introduction to Biology). While she understands that not all students are excited to take a required class such as 7.012, Mehrotra enjoys helping them engage with the content in meaningful ways.

“I just don’t see a better use of gaining knowledge than spreading it to other people,” she says.

Mehrotra is also a member of MIT’s women’s lightweight crew team. As the coxswain, she steers the boat and directs the other rowers both technically and motivationally during practices and races. She says the position has helped her develop her teamwork and leadership skills and allowed her to learn something new that she had never done before MIT. “It has been a great exercise in learning to be a leader and learning what I can do to support people even if I’m not experiencing exactly what they are, which is something I will have to do long term in my career as well,” she says.

Mehrotra will attend Stanford Medical School in the fall, with the goal of becoming a physician-scientist, dedicated to sharing knowledge, doing science, and interfacing with humanistic issues. Mehrotra wants to work directly with patients and researchers to solve medical issues, discovering new information and working with people who bring diverse perspectives. In the long run, she would like to start her own multidisciplinary research practice, where she envisions being able to see and treat patients some days a week, while also running a lab with different types of researchers, such as technical and social scientists.

For now, she is savoring the last few months of her time at MIT. “I’m happiest when I’m going around doing different things. It’s a shame I have to graduate now because there’s so much more to be done!” she says.

Pioneering a deeper understanding of metabolism

Merrill Meadow | Whitehead Institute

March 23, 2022

Metabolism is the sum of life-sustaining chemical reactions occurring in cells and across whole organisms. The human genome codes for thousands of metabolic enzymes, and specific metabolic pathways play significant roles in many biological processes—from breaking down food to release energy, to normal proliferation and differentiation of cells, to pathologies underlying diabetes, cancer, and other diseases.

For decades, Whitehead Institute researchers have helped both to clarify how metabolism works in healthy states and to identify how metabolic processes gone awry contribute to diseases. Among Whitehead Founding Member Harvey Lodish’s wide-ranging accomplishments, for example, are the identification of genes and proteins involved in development of insulin resistance and stress responses in fat cells. His lab explored the hormones controlling fatty acid and glucose metabolism, broadening understanding of obesity and type 2 diabetes. In 1995, the lab cloned adiponectin, a hormone made exclusively by fat cells. A long series of studies has shown that adiponectin causes muscle to burn fatty acids faster – so they are not stored as fat – and increases the metabolism of the sugar glucose. More recently the lab identified and characterized types of RNAs that are specifically expressed in fat cells – including a microRNA unique to brown fat, which burns rather than stores fatty acids. In addition, former Member David Sabatini’s discovery of the mTOR protein and his subsequent work elaborating many ways in which the mTOR pathway affects cells function has proven to be fundamental to understanding the relationship between metabolism and an array of diseases.

Today, Institute researchers continue to pioneer a deeper understanding of how metabolic processes contribute to health and disease – with long-term implications that could range from new treatments for obesity and type 2 diabetes to methods for slowing the aging process. Here are a few examples of Whitehead Institute scientists’ creative and pioneering work in the field of metabolism.

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Research inspiration comes in many forms. For example, Whitehead Institute Member Siniša Hrvatin – who joined the faculty in January 2022 from Harvard Medical School (HMS) – was inspired to pursue his current research by science-fiction tales about suspended animation for long-term space travel. And during graduate school, he realized that the ability of some mammals to enter a state of greatly reduced metabolism – such as occurs in hibernation – was a mild but real-world form of suspended animation.

Hrvatin’s doctoral research in Doug Melton’s lab at Harvard University focused primarily on stem cell biology. But his subsequent postdoctoral research positions at Massachusetts Institute of Technology (MIT) and HMS enabled him to begin exploring the mechanisms and impact of reduced metabolic states in mammals. The timing was serendipitous, too, because he was able to use the growing array of genetic tools that were becoming available – and create some new tools of his own as well.

“To survive extreme environments, many animals have evolved the ability to profoundly decrease metabolic rate and body temperature and enter states of dormancy, such as hibernation and torpor,” Hrvatin says. Hibernating animals enter repeated states of significantly reduced metabolic activity, each lasting days to weeks. By comparison, daily torpor is shorter, with animals entering repeated periods of lower-than-normal metabolic activity lasting several hours.

Hrvatin’s lab studies the mysteries of how animals and their cells initiate, regulate, and survive these adaptations. “Our long-term goal is to determine if these adaptations can be harnessed to create therapeutic applications for humans.” He and his team are focusing on three broad questions regarding the mechanisms underlying netbet online sports bettingtorpor in mice and hibernation in hamsters.

First: How do the animals’ brains initiate and regulate the metabolic processes involved in this process? During his postdoctoral research, Hrvatin published details of his discovery of neurons involved in the regulation of mouse torpor. “Now we are investigating how these torpor-regulating neurons receive information about the body’s energy-state,” he explains, “and studying how these neurons then drive a decrease of metabolic rate and body temperature throughout the body.”

Second: How do individual cells – and their genomes – adapt to extreme or changing environments; and how do these adaptations differ between types of organisms?

“Cells from hibernating organisms ranging from rodents to bears have evolved the ability to survive extreme cold temperatures for many weeks to months,” Hrvatin notes. “We are using genetic screens to identify species-specific mechanisms of tolerance to extreme cold. Then we will explore whether these mechanisms can be induced in non-hibernating organisms – potentially to provide health benefits.”

Third: Can we deliberately and specifically slow down tissue damage, disease progression, and or aging in cells and whole organisms by inducing torpor or hibernation – or facets of those states? It has long been known that hibernating animals live longer than closely related non-hibernators; that cancer cells do not replicate during hibernation; and that cold can help protect neurons from the effects of loss of oxygen. However, the cellular mechanisms underlying these phenomena remain largely unknown. Hrvatin’s lab will induce a long-term hibernation-like state in mice and natural hibernation in hamsters, and study how those states affect processes such as tissue repair, cancer progression, and aging.

“In the lab, if you take many human cell types and put them in a cold environment they die, but cells from hibernators survive,” Hrvatin notes. “We’re fascinated by the cellular processes underlying those survival capacities. As a starting place, we are using novel CRISPR screening approaches to help us identify the genomic mechanisms involved.”

And then? “Ultimately, we hope to take on the biggest question: Is it possible to transfer some of those survival abilities to humans?

Solving a mitochondrial conundrum

When Whitehead Institute postdoctoral researcher Jessica Spinelli was studying cancer metabolism in graduate school, she became interested in what seemed to be a scientific paradox regarding mitochondria, the cell’s energy-producing organelles: Mitochondria are believed to be important for tumor growth; but they generally need oxygen to function, and substantial portions of tumors have very low oxygen levels. Pursuing research in the lab of former Whitehead Institute Member David Sabatini, Spinelli sought to understand how those facts fit together and whether mitochondria could somehow adapt to function with limited oxygen levels.

Recently, Spinelli and colleagues published an answer to the conundrum – one that could inform research into medical conditions including ischemia, diabetes and cancer. In a Science paper for which Spinelli was first author, the team demonstrated that when cells are deprived of oxygen, a molecule called fumarate can serve as a substitute and enable mitochondria to continue functioning.

As Spinelli explains, humans need oxygen molecules for the cellular respiration process that takes place in our cells’ mitochondria. In this process – called the electron transport chain – electrons are passed along in a sort of cellular relay race that, ultimately, allows the cell to create the energy needed to perform its vital functions. Usually, oxygen is necessary to keep that process operating.

Using mass spectrometry to measure the quantities of molecules produced through cellular respiration in varied conditions, Spinelli and the team found that cells deprived of oxygen had a high level of succinate molecules, which form when electrons are added to a molecule called fumarate. “From this, we hypothesized that the accumulation of succinate in low-oxygen environments is caused by mitochondria using fumarate as a substitute for oxygen’s role in the electron transport chain,” Spinelli explains. “That could explain how mitochondria function with relatively little oxygen.” The next step was to test that hypothesis in mice, and those studies provided several interesting findings: Only mitochondria in kidney, liver, and brain tissues could use fumarate in the electron transport chain. And even in normal conditions, mitochondria in these tissues used both fumarate and oxygen to function – shifting to rely more heavily on fumarate when oxygen was reduced. In contrast, heart and skeletal muscle mitochondria made minimal use of fumarate and did not function well with limited oxygen.

“We foresee some exciting work ahead, learning exactly how this process is regulated in different tissues,” Spinelli says, “and, especially, in solid tumor cancers, where oxygen levels vary between regions.”

Seeking a more accurate model of diabetes

Max Friesen, a postdoctoral researcher in the lab of Whitehead Institute Founding Member Rudolf Jaenisch, studies the role of cell metabolism in type 2 diabetes (T2D). An increasingly prevalent disease that affects millions of people around the world, T2D is hard to study in the lab. This has made it very challenging for scientists to detail the cellular mechanisms through which it develops – and therefore to create effective therapeutics.

“It has always been very hard to model T2D, because metabolism differs greatly between species,” Friesen says. “That fact leads to complications when we use animal models to study this disease. Mice, for example, have much higher metabolism and faster heart rates than humans. As a result, researchers have developed many approaches that cure diabetes in mice but that fail in humans.” Nor do most in vitro culture systems—cells in a dish—effectively recapitulate the disease.

But, building on Jaenisch’s pioneering success in developing disease models derived from human stem cells, Friesen is working to create a much more accurate in vitro system for studying diabetes. His goal is to make human stem cell-derived tissues that function as they would in the human body, closely recapitulating what happens when an individual develops diabetes. Currently, Friesen is differentiating human stem cells into metabolic tissues such as liver and adipocytes (fat). He has improved current differentiation protocols by adapting these cells to a culture medium that is much closer to the environment they see in the human body. Serendipitously, the process also makes the cells responsive to insulin at levels that are present in the human bloodstream. “This serves as a great model of a healthy cell that we can then turn into a disease model by exposing the cell to diabetic hyperinsulinemia,” Friesen says.

These advances should enable him to gain a better understanding of how metabolic pathways – such as the insulin signaling pathway – function in a diabetic model versus a healthy control model. “My hope is that our new models will enable us to figure out how dietary insulin resistance develops, and then identify a therapeutic intervention that blocks that disease-causing process,” he explains. “It would be fantastic to help alleviate this growing global health burden.”

Alumna, Margaret ‘Mo’ Okobi ’16, prepares for a career combining medicine and public health research to improve mental health care services in vulnerable communities

Leah Campbell | School of Science

March 22, 2022

With only one year left of medical school at Harvard, Mo Okobi ’16, took a leave of absence. She didn’t want to take a break as much as a “step back” — a moment to reassess and reframe what she was learning in school within the bigger picture of the U.S. healthcare system. During that year, Okobi earned her master’s in public health from the Harvard School of Public Health.

“It’s so important to keep a broader view of the trends in medicine,” she says, “to look at what medications and therapies we’re using and what is actually working for patients.”

When she applied to the MPH program, Okobi couldn’t have known that her year-long leave to study public health would overlap with a pandemic. Needless to say, it was good timing. Okobi’s joint training in public health and medicine has also uniquely positioned her for a career combining clinical practice and research around chronic mental illness.

Though she says she never expected to find herself on this path, Okobi’s experiences at MIT shaped her approach to medicine and her commitment to providing quality mental healthcare to underserved communities.

Okobi was interested in many aspects of medicine when she enrolled at MIT. She majored in biology, with a minor in chemistry, to explore her broad interests in STEM. She joined MIT Emergency Medical Services, a student-run, volunteer ambulance service, for the same reason.

Being a certified EMT, though, she says, was one of the most formative aspects of her MIT education. She describes it as an “intensive introduction to medicine,” cementing her excitement about her future as a doctor. It was also one of her first exposures to mental health care, and Okobi believes that mental health emergencies made up a large proportion, if not a majority, of their calls.

“MIT EMS was really my first opportunity to actually work with patients very closely and see them in their moments of need,” she says.

While deciding to become a doctor was easy, Okobi’s journey to research wasn’t so smooth. She participated in one official undergraduate research experience at MIT, admitting, “I kind of hated it.” Working in a basic science biology lab, Okobi realized that the bench wasn’t for her.

Fortunately, her mentor, Hazel Sive, a former MIT professor of biology and now Dean of the College of Science at Northeastern University, took the time to talk with Okobi and figure out where she’d thrive. Sive, a South African, connected Okobi with the MIT Africa Program, through which she spent a summer in Johannesburg with the South African National Health Laboratory Services.

That experience, which she describes as a “pivotal framing moment,” helped Okobi understand how a career combining clinical practice and research might look. She worked with scientists studying HIV transmission from mother to child, assessing the quality of testing and resource gaps across different provinces. Near the end of her internship, Okobi was able to go into an HIV clinic and do antibody testing.

“I’m looking at these numbers. I’m making all these graphs and writing this paper, but I’m also seeing the people,” she says. “I loved the clinical work. I loved meeting people and knowing their stories.”

At graduation, Okobi was recognized as a Ronald E. McNair Scholar, an award that goes every year to Black undergraduates who have excelled academically and contributed to the experience of students on campus from underrepresented groups. The award was established in honor of McNair, PhD ’77, an accomplished astronaut who received his doctorate in physics from MIT and tragically perished onboard the Challenger space shuttle in 1986.

Having found a passion for applied, public health research, Okobi spent a year before medical school at a healthcare data analytics startup called Aetion. Aetion uses data from hospitals and insurance companies to analyze healthcare trends like medication usage and clinical outcomes. For a self-described “numbers nerd” like Okobi, it was a great way to learn how healthcare studies are designed and see the big picture behind clinical decisions.

It was her second year of medical school, though, that focused Okobi’s health interests around psychiatry for marginalized populations. During her clinical rotations, she worked at Cambridge Health Alliance (CHA), a public, community-centered hospital. At CHA, she served many non-English speakers and MassHealth recipients and was able to do rotations in outpatient, inpatient, and emergency psychiatric settings.

“I really got to see it from all angles,” Okobi says of her psychiatry rotations. “I loved the practice of creating space for people to talk about their lives…. it’s about the medicine and mental illness, but it’s also about seeing the whole person.”

As for what’s next, Okobi will be heading west for her residency in psychiatry at the University of California San Francisco.

Her work with CHA convinced Okobi to apply for residencies in psychiatry. She’s primarily interested in acute care settings, particularly for those with severe, chronic mental illnesses like schizophrenia. For her, one of the joys of netbet online sports bettinginpatient care is working closely with patients on a daily basis, to, as she describes it, “try to leave a positive, lasting impression on those first encountering psychiatric care.”

Yet, armed with her degree in public health, she’s also committing to combining her clinical practice with ongoing research. At Harvard, she organized a mental health survey for medical and dental students in her class to improve access to mental health resources. Since 2020, she’s been participating in research on psychiatric emergency care utilization with the Boston Emergency Services Team. In 2020, she returned to Aetion as a consultant with their new FDA-backed COVID-19 research group, to lead epidemiological studies examining COVID-19 risk factors.

Looking back, Okobi knows that it may seem like she had a clear professional plan from the get-go. But she stresses that that wasn’t her experience at all, and current students should understand that things have a way of working out if you’re open to trying things.

“My path was very much like ping pong, never knowing where I’m going next,” she says. “The uncertainty never really ends, but I take refuge in those moments of serendipity, when I find something or someone that excites me and challenges me to be a better version of myself.”

Yukiko Yamashita, unraveler of stem cells’ secrets

The MIT biologist’s research has shed light on the immortality of germline cells and the function of “junk DNA.”

Anne Trafton | MIT News Office

March 22, 2022

When cells divide, they usually generate two identical daughter cells. However, there are some important exceptions to this rule: When stem cells divide, they often produce one differentiated cell along with another stem cell, to maintain the pool of stem cells.

Yukiko Yamashita has spent much of her career exploring how these “asymmetrical” cell divisions occur. These processes are critically important not only for cells to develop into different types of tissue, but also for germline cells such as eggs and sperm to maintain their viability from generation to generation.

“We came from our parents’ germ cells, who used to be also single cells who came from the germ cells of their parents, who used to be single cells that came from their parents, and so on. That means our existence can be tracked through the history of multicellular life,” Yamashita says. “How germ cells manage to not go extinct, while our somatic cells cannot last that long, is a fascinating question.”

Yamashita, who began her faculty career at the University of Michigan, joined MIT and the Whitehead Institute in 2020, as the inaugural holder of the Susan Lindquist Chair for Women in Science and a professor in the Department of Biology. She was drawn to MIT, she says, by the eagerness to explore new ideas that she found among other scientists.

“When I visited MIT, I really enjoyed talking to people here,” she says. “They are very curious, and they are very open to unconventional ideas. I realized I would have a lot of fun if I came here.”

Exploring paradoxes

Before she even knew what a scientist was, Yamashita knew that she wanted to be one.

“My father was an admirer of Albert Einstein, so because of that, I grew up thinking that the pursuit of the truth is the best thing you could do with your life,” she recalls. “At the age of 2 or 3, I didn’t know there was such a thing as a professor, or such a thing as a scientist, but I thought doing science was probably the coolest thing I could do.”

Yamashita majored in biology at Kyoto University and then stayed to pursue her PhD, studying how cells make exact copies of themselves when they divide. As a postdoc at Stanford University, she became interested in the exceptions to that carefully orchestrated process, and began to study how cells undergo divisions that produce daughter cells that are not identical. This kind of asymmetric division is critical for multicellular organisms, which begin life as a single cell that eventually differentiates into many types of tissue.

Those studies led to a discovery that helped to overturn previous theories about the role of so-called junk DNA. These sequences, which make up most of the genome, were thought to be essentially useless because they don’t code for any proteins. To Yamashita, it seemed paradoxical that cells would carry so much DNA that wasn’t serving any purpose.

“I couldn’t really believe that huge amount of our DNA is junk, because every time a cell divides, it still has the burden of replicating that junk,” she says. “So, my lab started studying the function of that junk, and then we realized it is a really important part of the chromosome.”

In human cells, the genome is stored on 23 pairs of chromosomes. Keeping all of those chromosomes together is critical to cells’ ability to copy genes when they are needed. Over several years, Yamashita and her colleagues at the University of Michigan, and then at MIT, discovered that stretches of junk DNA act like bar codes, labeling each chromosome and helping them bind to proteins that bundle chromosomes together within the cell nucleus.

Without those barcodes, chromosomes scatter and start to leak out of the cell’s nucleus. Another intriguing observation regarding these stretches of junk DNA was that they have much greater variability between different species than protein-coding regions of DNA. By crossing two different species of fruit flies, Yamashita showed that in cells of the hybrid offspring flies, chromosomes leak out just as they would if they lost their barcodes, suggesting that the codes are specific to each species.

“We think that might be one of the big reasons why different species become incompatible, because they don’t have the right information to bundle all of their chromosomes together into one place,” Yamashita says.

Stem cell longevity

Yamashita’s interest in stem cells also led her to study how germline cells (the cells that give rise to eggs and sperm cells) maintain their viability so much longer than regular body cells across generations. In typical animal cells, one factor that contributes to age-related decline is loss of genetic sequences that encode genes that cells use continuously, such as genes for ribosomal RNAs.

A typical human cell may have hundreds of copies of these critical genes, but as cells age, they lose some of them. For germline cells, this can be detrimental because if the numbers get too low, the cells can no longer form viable daughter cells.

Yamashita and her colleagues found that germline cells overcome this by tearing sections of DNA out of one daughter cell during cell division and transferring them to the other daughter cell. That way, one daughter cell has the full complement of those genes restored, while the other cell is sacrificed.

That wasteful strategy would likely be too extravagant to work for all cells in the body, but for the small population of germline cells, the tradeoff is worthwhile, Yamashita says.

“If skin cells did that kind of thing, where every time you make one cell, you are essentially trashing the other one, you couldn’t afford it. You would be wasting too many resources,” she says. “Germ cells are not critical for viability of an organism. You have the luxury to put many resources into them but then let only half of the cells recover.”

A Picower Institute primer on ‘plasticity,’ the brain’s amazing ability to constantly adapt to and learn from experience

Picower Institute

March 17, 2022

Muscles and bones strengthen with exercise and the immune system ‘learns’ from vaccines or infections, but none of those changes match the versatility and flexibility your central nervous system shows in adapting to the world. The brain is a model remodeler. If it weren’t, you wouldn’t have learned how to read this and you wouldn’t remember it anyway.

The brain’s ability to change its cells, their circuit connections, and even its broader architectures in response to experience and activity, for instance to learn new rules and store memories, is called “plasticity.” The phenomenon explains how the brand-new brain of an infant can emerge from a womb and make increasingly refined sense of whatever arbitrary world it encounters – ranging from tuning its visual perception in the early months to getting an A in eighth-grade French. Plasticity becomes subtler during adulthood, but it never stops. It occurs via so many different mechanisms and at so many different scales and rates, it’s… mind-bending.

Plasticity’s indispensable role in allowing the brain to incorporate experience has made understanding exactly how it works – and what the mental health ramifications are when it doesn’t – the inspiration and research focus of several Picower Institute professors (and hundreds of colleagues). This site uses the term so often in reports on both fundamental neuroscience and on disorders such as autism, it seemed high time to provide a primer. So here goes.

Beginning in the 1980s and 1990s, advances in neuroanatomy, genetics, molecular biology and imaging made it possible to not only observe, but even experimentally manipulate mechanisms of how the brain changes at scales including the individual connections between neurons, called synapses; across groups of synapses on each neuron; and in whole neural circuits. The potential to discover tangible physical mechanisms of these changes proved irresistible to Picower Institute scientists such as Mark Bear, Troy Littleton, Elly Nedivi and Mriganka Sur.

Bear got hooked by experiments in which by temporarily covering one eye of a young animal, scientists could weaken the eye’s connections to the brain just as their visual circuitry was still developing. Such “monocular deprivation” produced profound changes in brain anatomy and neuronal electrical activity as neurons rewired circuits to support the unobstructed eye rather than the one with weakened activity.

“There was this enormous effect of experience on the physiology of the brain and a very clear anatomical basis for that,” Bear said. “It was pretty exhilarating.”

Littleton became inspired during graduate and medical school by new ways to identify genes whose protein products formed the components of synapses. To understand how synapses work was to understand how neurons communicate and therefore how the brain functions.

“Once we were able to think about the proteins that are required to make the whole engine work, we could figure out how you might rev it up and down to encode changes in the way the system might be working to increase or decrease information flow as a function of behavioral change,” Littleton said.

Built to rebuild

So what is the lay of the land for plasticity? Start with a neuron. Though there are thousands of types, a typical neuron will extend a vine-like axon to forge synapses on the root-like dendrites of other neurons. These dendrites may host thousands of synapses. Whenever neurons connect, they form circuits that can relay information across the brain via electrical and chemical signals. Most synapses are meant to increase the electrical excitement of the receiving neuron so that it will eventually pass a signal along, but other synapses modulate that process by inhibiting activity.

Hundreds of proteins are involved in building and operating every synapse, both on the “pre-synaptic” (axonal) side and the “post-synaptic” (dendritic) side of the connection. Some of these proteins contribute to the synapse’s structure. Some on the pre-synaptic side coordinate the release of chemicals called neurotransmitters from blobs called vesicles, while some on the postsynaptic side form or manage the receptors that receive those messages. Neurotransmitters may compel the receiving neuron to take in more ions (hence building up electric charge), but synapses aren’t just passive relay stations of current. They adjust in innumerable ways according to changing conditions, such as the amount of communication activity the host cells are experiencing. Across many synapses the pace and amount of neurotransmitter signaling can be frequently changed by either the presynaptic or postsynaptic side. And sometimes, especially early in life, synapses will appear or disappear altogether.

Moreover, plasticity doesn’t just occur at the level of the single synapse. Combinations of synapses along a section of dendrite can all change in coordination so that the way a neuron works within a circuit is altered. NetBet live casinoThese numerous dimensions of plasticity help to explain how the brain can quickly and efficiently accomplish the physical implementation of something as complex as learning and memory, Nedivi said.

“You might think that when you learn something new it has nothing to do with individual synapses,” Nedivi said. “But in fact, the way that things like this happen is that individual synapses can change in strength or can be added and removed, and then it also matters which synapses, and how many synapses, and how they are organized on the dendrites, and how those changes are integrated and summated on the cell. These parameters will alter the cell’s response properties within its circuit and that affects how the circuit works and how it affects behavior.”

A 2018 study in Sur’s lab illustrated learning occurring at a neural circuit level. His lab trained mice on a task where they had to take a physical action based on a visual cue (e.g. drivers know that “green means go”). As mice played the game, the scientists monitored neural circuits in a region called the posterior parietal cortex where the brain converts vision into action. There, ensembles of neurons increased activity specifically in response the “go” cue. When the researchers then changed the game’s rules (i.e. “red means go”) the circuits switched to only respond to the new go cue. Plasticity had occurred en masse to implement learning.

Many mechanisms

To carry out that rewiring, synapses can change in many ways. Littleton’s studies of synaptic protein components have revealed many examples of how they make plasticity happen. Working in the instructive model of the fruit fly, his lab is constantly making new findings that illustrate how changes in protein composition can modulate synaptic strength.

For instance, in a 2020 study his lab showed that synaptotagmin 7 limits neurotransmitter release by regulating the speed with which the supply of neurotransmitter-carrying vesicles becomes replenished. By manipulating expression of the protein’s gene, his lab was able to crank neurotransmitter release, and therefore synaptic strength, up or down like a radio volume dial.

Other recent studies revealed how proteins influence the diversity of neural plasticity. At the synapses flies use to control muscles, “phasic” neurons release quick, big bursts of the neurotransmitter glutamate, while tonic ones steadily release a low amount. In 2020 Littleton’s lab showed that when phasic neurons are disrupted, tonic neurons will plasticly step up glutamate release, but phasic ones don’t return the favor when tonic ones are hindered. Then last year, his team showed that a major difference between the two neurons was their levels of a protein called tomosyn, which turns out to restrict glutamate release. Tonic ones have a lot but phasic ones have very little. Tonic neurons therefore can vary their glutamate release by reducing tomosyn expression, while phasic neurons lack that flexibility.

Nedivi, too, looks at how neurons use their genes and the proteins they encode to implement plasticity. She tracks “structural plasticity” in the living mouse brain, where synapses don’t just strengthen or weaken, but come and go completely. She’s found that even in adult animal brains, inhibitory synapses will transiently appear or disappear to regulate the influence of more permanent excitatory synapses.

Nedivi has revealed how experience can make excitatory synapses permanent. After discovering that mice lacking a synaptic protein called CPG15 were slow learners, Nedivi hypothesized that it was because the protein helped cement circuit connections that implement learning. To test that, her lab exposed normal mice and others lacking CPG15 to stretches of time in the light, when they could gain visual experience, and the dark, where there was no visual experience. Using special microscopes to literally watch fledgling synapses come and go in response, they could compare protein levels in those synapses in normal mice and the ones without CPG15. They found that CPG15 helped experience make synapses stick around because upon exposure to increased activity, CPG15 recruited a structural protein called PSD95 to solidify the synapses. That explained why CPG15-lacking mice don’t learn as well: they lack that mechanism for experience and activity to stabilize their circuit connections.

Another Sur Lab study in 2018 helped to show how multiple synapses sometimes change in concert to implement plasticity. Focusing on a visual cortex neuron whose job was to respond to locations within a mouse’s field of view, his team purposely changed which location it preferred by manipulating “spike-timing dependent plasticity.” Essentially right after they put a visual stimulus in a new location (rather than the neuron’s preferred one), they artificially excited the neuron. The reinforcement of this specifically timed excitement strengthened the synapse that received input about the new location. After about 100 repetitions, the neuron changed its preference to the new location. Not only did the corresponding synapse strengthen, but also the researchers saw a compensatory weakening among neighboring synapses (orchestrated by a protein called Arc). In this way, the neuron learned a new role and shifted the strength of several synapses along a dendrite to ensure that new focus.

Lest one think that plasticity is all about synapses or even dendrites, Nedivi has helped to show that it isn’t. For instance, her research has shown that amid monocular deprivation, inhibitory neurons go so far as to pare down their axons to enable circuit rewiring to occur. In 2020 her lab collaborated with Harvard scientists to show that to respond to changes in visual experience, some neurons will even adjust how well they insulate their axons with a fatty sheathing called myelin that promotes electrical conductance. The study added strong evidence that myelination also contributes to the brain’s adaptation to changing experience.

It’s not clear why the brain has evolved so many different ways to effect change (these examples are but a small sampling) but Nedivi points out a couple of advantages: robustness and versatility.

“Whenever you see what seems to you like redundancy it usually means it’s a really important process. You can’t afford to have just one way of doing it,” she said. “Also having multiple ways of doing things gives you more precision and flexibility and the ability to work over multiple time scales, too.”

Insights into illness

Another way to appreciate the importance of plasticity is to recognize its central role in neurodevelopmental diseases and conditions. Through their fundamental research into plasticity mechanisms, Bear, Littleton, Nedivi and Sur have all discovered how pivotal they are to breakdowns in brain health.

Beginning in the early 1990s, Bear led pioneering experiments showing that by multiple means, post-synaptic sensitivity could decline when receptors received only weak input, a plasticity called long-term depression (LTD). LTD explained how monocular deprivation weakens an occluded eye’s connections to the brain. Unfortunately, this occurs naturally in millions of children with visual impairment, resulting in a developmental vision disorder called amblyopia. But Bear’s research on plasticity, including mechanisms of LTD, has also revealed that plasticity itself is plastic (he calls that “metaplasticity”). That insight has allowed his lab to develop a potential new treatment in which by completely but temporarily suspending all input to the affected eye by anesthetizing the retina, the threshold for strengthening vs. weakening can be lowered such that when input resumes, it triggers a newly restorative connection.

Bear’s investigations of a specific form of LTD have also led to key discoveries about Fragile X syndrome, a genetic cause of autism and intellectual disability. He found that LTD can occur when stimulation of metabotropic glutamate receptor 5 (mGluR5) causes proteins to be synthesized at the dendrite, reducing post-synaptic sensitivity. A protein called FMRP is supposed to be a brake on this synthesis but mutation of the FMR1 gene in Fragile X causes loss of FMRP. That can exaggerate LTD in the hippocampus, a brain region crucial for memory and cognition. The insight has allowed Bear to advance drugs to clinical trials that inhibit MGlur5 activity to compensate for FMRP loss.

Littleton, too, has produced insight into autism by studying the consequences of mutation in the gene Shank3, which encodes a protein that helps to build developing synapses on the post-synaptic side. In a 2016 paper his team reported multiple problems in synapses when Shank was knocked out in fruit flies. Receptors for a key form of molecular signaling from the presynaptic side called Wnt failed to be internalized by the postsynaptic cell, meaning they could not influence the transcription of genes that promote maturation of the synapse as they normally would. A consequence of disrupted synaptic maturation is that a developing brain would struggle to complete the connections needed to efficiently encode experience and that may explain some of the cognitive and behavioral outcomes in Shank-associated autism. To set the stage for potential drug development, Littleton’s lab was able to demonstrate ways to bypass Wnt signaling that rescued synaptic development.

By studying plasticity proteins Sur’s lab, too, has discovered a potential way to help people with Rett syndrome, a severe autism-like disorder. The disease is caused by mutations in the gene MECP2. Sur’s lab showed that MECP2’s contribution to synaptic maturation comes via a protein called IGF1 that is reduced among people with Rett. That insight allowed them to show that treating Rett-model mice with extra IGF1 peptide or IGF1 corrected many defects of MECP2 mutation. Both treatment forms have advanced to clinical trials. Late last year IGF1 peptide was shown to be effective in a comprehensive phase 3 trial for Rett syndrome and is progressing toward FDA approval as the first-ever mechanism-based treatment for a neurodevelopmental disorder, Sur said.

Nedivi’s plasticity studies, meanwhile, have yielded new insights into bipolar disorder. During years of fundamental studies, Nedivi discovered CPG2, a protein expressed in response to neural activity that helps regulate the number of glutamate receptors at excitatory synapses. The gene encoding CPG2 was recently identified as a risk gene for bipolar disorder. In a 2019 study her lab found that people with bipolar disorder indeed had reduced levels of CPG2 because of variations in the SYNE1 gene. When they cloned these variants into rats, they found they reduced the ability of CPG2 to locate in the dendritic “spines” that house excitatory synapses or decreased the proper cycling of glutamate receptors within synapses.

The brain’s ever-changing nature makes it both wonderful and perhaps vulnerable. Both to understand it and heal it, neuroscientists will eagerly continue studying its plasticity for a long time to come.

Life sciences class brings biotech industry experience into the classroom with part-time internships for graduate students.

Leah Campbell | School of Science

March 9, 2022

Kendall Square has been called the most innovative square mile in the United States, in part due to the high density of biotechnology and biopharmaceutical companies in the MIT-adjacent neighborhood of Cambridge, Massachusetts — but more so thanks to the generations of MIT-trained doctoral students who have pursued careers in these local companies after graduation. Yet, that innovation ecosystem remains a mystery for many current students.

“Many, or even most, graduate students have no substantive experience with the biopharma industry netbet sports bettingdespite the likelihood that they will pursue careers in this realm,” says Doug Lauffenburger, the Ford Professor of Biological Engineering, Chemical Engineering, and Biology. For the last several years, the departments of Biology and Biological Engineering have tried to better inform and prepare their students for that possibility with 7.930/20.930 (Research Experience in Biopharma), a for-credit class providing late-stage doctoral students with hands-on experience in industry.

“It’s really designed to demystify doing research in industry,” says Amy Keating, a professor of biology and biological engineering. “The feedback we get suggests it’s quite eye-opening in terms of changing some assumptions about what that life is like.”

The class has been offered annually since Spring 2016. Most recently offered this past fall, it’s co-taught by Keating and Sean Clarke, a communications instructor and manager of biotech outreach within the Department of Biological Engineering. Participants spend most of their time at part-time internships with local biotech and biopharma companies working on semester-long projects.

“The emphasis really is more on the experience than the particular project or hitting some milestone,” says Clarke. He explains that industry partners offer up potential projects, and students are matched “so that they’re close enough in expertise and interest, but not directly overlapping with thesis work or so outrageous that they can’t be contributors.”

Most students are based in the departments of Biology and Biological Engineering, but others have come from Chemistry, Mechanical Engineering, Brain and Cognitive Sciences, and the Harvard-MIT Program in Health Sciences and Technology. Clarke and Keating say that almost all participants have gone on to pursue industry careers, sometimes at the companies that hosted them during the class.

Student ideas for student opportunities

Lauffenburger, Keating, and Clarke all stress that the driving force behind the class in its early days was students. In particular, they highlight the contributions of Raven Reddy PhD ’17 and Nathan Stebbins PhD ’17, two former biological engineering doctoral students.

“It’s a good example of identifying an excellent idea that came from students themselves and simply putting departmental support, attention, and resources behind it,” says Lauffenburger.

Reddy and Stebbins were two of the early leaders of the MIT Biotechnology Group, a student-led organization designed precisely to expose students to the world of industry. In brainstorming with members how best to explore potential careers path, “part-time internships were far and away one of the most popular things that people said would be a really enriching experience,” says Reddy, now vice president of science operations at BridgeBio Pharma in Palo Alto, California.

The industry representatives they approached were thrilled by the opportunity to host MIT PhD students; so, Reddy and Stebbins sought out a way to make part-time internships possible. Given time constraints on students and their advisors — and legal constraints for companies — they landed on a class as the best possible arrangement.

Formatting the experience as a class was a “win-win scenario on all sides that decreased the barrier to entry for every party,” says Stebbins, now a principal at Flagship Pioneering, a life sciences investment group in Cambridge.

Stebbins and Reddy were listed as co-teachers that first semester. It’s been taught every year since, with Lauffenburger, Keating, and Clarke keeping the momentum going after Stebbins and Reddy graduated and began their own careers in the private sector.

Outside perspective

While the focus of the Research Experience in Biopharma class is on the internship, students spend one hour per week in the classroom together to hear from guest lecturers, make contacts in industry, and build professional development skills.

This past fall, one such guest speaker was Becky Kusko ’09, one of the first undergraduates in the Department of Biological Engineering. After getting her PhD in genetics and genomics at Boston University in 2014, she now works for Immuneering Corporation, a local company that uses bioinformatics technology to streamline drug development.

In October 2021, Kusko spoke to students in the class to describe her own transition from academia to the private sector and provide a “behind-the-scenes” look at day-to-day life in biotech. She says she’s envious that students have this opportunity to explore their options now. Personally, she says, she had “zero interest” in — or understanding of — the private sector until a series of happy accidents took her to Immuneering as she wrapped up her dissertation.

“I had my list of 72 reasons why I was perfectly cut out for academia,” she says, “but then I realized all of those things I could do in an industry career.” During her time at Immuneering, she says, she’s published in peer-review journals, mentored students, and presented at conferences — all things she assumed were limited to the academic track. Her take-home message for the students was simply to be open-minded to different opportunities.

Ongoing benefits

Kusko’s lecture was a highlight of the class for Allen Sanderlin, a fifth-year graduate student in biology, who says he’s always been interested in the industry route and enrolled in the class to explore that possibility further. The fact that it’s a for-credit class, he says, means it’s more “regimented” than a speaker series or seminar, and so it felt easier to fit into his schedule and more reflective of the actual experience of working at a company.

During his internship this past fall, Sanderlin worked with the functional genomics team at Pfizer, helping to identify target genes and determine if certain equipment and techniques are worth investing in. “We’re at the very start of the drug pipeline,” he says. “It’s like nothing I’ve done before.”

That’s not to say that there haven’t been parallels between his internship and his doctoral work in the lab of Becky Lamason, the Robert A. Swanson Career Development Professor of Biology. “Fundamentally, they’re very different things, but at the same time, the skills and techniques I’ve learned in the lab, like tissue culturing, have helped,” he says. Similarly, what he’s learned at Pfizer about managing huge numbers of samples and automating processes has inspired him to find ways to be more efficient in his own work.

Anna Yeh is another fifth-year student in biology. Like Sanderlin, Yeh was always interested in industry but wasn’t sure of what that life entailed.

“Before this, I’ve just been purely in an academic setting,” Yeh says. “This seemed like a nice contained, low-bar way to be exposed to the industry career path.”

Like Sanderlin, Yeh was based at Pfizer for her internship, in the internal medicine unit, doing research totally unlike her doctoral work in the lab of Adam Martin, an associate professor of biology. At MIT, she uses flies to study how organisms come together into a coherent shape in the early stages of development. In contrast, at Pfizer, she worked with mice to see how increasing fructose in their diet affects liver health.

Yet, Yeh sees clear ways that her own research in molecular biology has helped her during her time at Pfizer, as well as how to incorporate skills from her internship into her own work going forward.

“The knowledge is definitely helpful,” she says, “just in terms of trying new things and using techniques I’ve only read about in papers.”

After taking the class, both Sanderlin and Yeh are more confident than ever about pursuing careers in industry. Their mentors at Pfizer, they say, have been invaluable helping them network, looking over their resumes, and discussing career options with them. Both also recommend the course wholeheartedly for future students.

“If anyone is unsure of whether they’d like to go into industry, this is a great class to get a taste of it,” says Yeh. “I think everyone should be aware of it as an option.”

An ‘oracle’ for predicting the evolution of gene regulation

Researchers created a mathematical framework to examine the genome and detect signatures of natural selection, deciphering the evolutionary past and future of non-coding DNA.

Raleigh McElvery

March 9, 2022

Despite the sheer number of genes that each human cell contains, these so-called “coding” DNA sequences comprise just 1% of our entire genome. The remaining 99% is made up of “non-coding” DNA — which, unlike coding DNA, does not carry the instructions to build proteins.

One vital function of this non-coding DNA, also called “regulatory” DNA, is to help turn genes on and off, controlling how much (if any) of a protein is made. Over time, as cells replicate their DNA to grow and divide, mutations often crop up in these non-coding regions — sometimes tweaking their function and changing the way they control gene expression. Many of these mutations are trivial, and some are even beneficial. Occasionally, though, they can be associated with increased risk of common diseases, such as type 2 diabetes, or more life-threatening ones, including cancer.

To better understand the repercussions of such mutations, researchers have been hard at work on mathematical maps that allow them to look at an organism’s genome, predict which genes will be expressed, and determine how that expression will affect the organism’s observable traits. These maps, called fitness landscapes, were conceptualized roughly a century ago to understand how genetic makeup influences one common measure of organismal fitness in particular: reproductive success. Early fitness landscapes were very simple, often focusing on a limited number of mutations. Much richer data sets are now available, but researchers still require additional tools to characterize and visualize such complex data. This ability would not only facilitate a better understanding of how individual genes have evolved over time, but would also help to predict what sequence and expression changes might occur in the future.

In a new study published on March 9 in Nature, a team of scientists has developed a framework for studying the fitness landscapes of regulatory DNA. They created a neural network model that, when trained on hundreds of millions of experimental measurements, was capable of predicting how changes to these non-coding sequences in yeast affected gene expression. They also devised a unique way of representing the landscapes in two dimensions, making it easy to understand the past and forecast the future evolution of non-coding sequences in organisms beyond yeast — and even design custom gene expression patterns for gene therapies and industrial applications.

“We now have an ‘oracle’ that can be queried to ask: What if we tried all possible mutations of this sequence? Or, what new sequence should we design to give us a desired expression?” says Aviv Regev, a professor of biology at MIT (on leave), core member of the Broad Institute of Harvard and MIT (on leave), head of Genentech Research and Early Development, and the study’s senior author. “Scientists can now use the model for their own evolutionary question or scenario, and for other problems like making sequences that control gene expression in desired ways. I am also excited about the possibilities for machine learning researchers interested in interpretability; they can ask their questions in reverse, to better understand the underlying biology.”

Prior to this study, many researchers had simply trained their models on known mutations (or slight variations thereof) that exist in nature. However, Regev’s team wanted to go a step further by creating their own unbiased models capable of predicting an organism’s fitness and gene expression based on any possible DNA sequence — even sequences they’d never seen before. This would also enable researchers to use such models to engineer cells for pharmaceutical purposes, including new treatments for cancer and autoimmune disorders.

To accomplish this goal, Eeshit Dhaval Vaishnav, a graduate student at MIT and co-first author, Carl de Boer, now an assistant professor at the University of British Columbia, and their colleagues created a neural network model to predict gene expression. They trained it on a dataset generated by inserting millions of totally random non-coding DNA sequences into yeast, and observing how each random sequence affected gene expression. They focused on a particular subset of non-coding DNA sequences called promoters, which serve as binding sites for proteins that can switch nearby genes on or off.

“This work highlights what possibilities open up when we design new kinds of experiments to NetBet sportgenerate the right data to train models,” Regev says. “In the broader sense, I believe these kinds of approaches will be important for many problems — like understanding genetic variants in regulatory regions that confer disease risk in the human genome, but also for predicting the impact of combinations of mutations, or designing new molecules.”

Regev, Vaishnav, de Boer, and their coauthors went on to test their model’s predictive abilities in a variety of ways, in order to show how it could help demystify the evolutionary past — and possible future — of certain promoters. “Creating an accurate model was certainly an accomplishment, but, to me, it was really just a starting point,” Vaishnav explains.

First, to determine whether their model could help with synthetic biology applications like producing antibiotics, enzymes, and food, the researchers practiced using it to design promoters that could generate desired expression levels for any gene of interest. They then scoured other scientific papers to identify fundamental evolutionary questions, in order to see if their model could help answer them. The team even went so far as to feed their model a real-world population data set from one existing study, which contained genetic information from yeast strains around the world. In doing so, they were able to delineate thousands of years of past selection pressures that sculpted the genomes of today’s yeast.

But, in order to create a powerful tool that could probe any genome, the researchers knew they’d need to find a way to forecast the evolution of non-coding sequences even without such a comprehensive population data set. To address this goal, Vaishnav and his colleagues devised a computational technique that allowed them to plot the predictions from their framework onto a two-dimensional graph. This helped them show, in a remarkably simple manner, how any non-coding DNA sequence would affect gene expression and fitness, without needing to conduct any time-consuming experiments at the lab bench.

“One of the unsolved problems in fitness landscapes was that we didn’t have an approach for visualizing them in a way that meaningfully captured the evolutionary properties of sequences,” Vaishnav explains. “I really wanted to find a way to fill that gap, and contribute to the longstanding vision of creating a complete fitness landscape.”

Martin Taylor, a professor of genetics at the University of Edinburgh’s Medical Research Council Human Genetics Unit who was not involved in the research, says the study shows that artificial intelligence can not only predict the effect of regulatory DNA changes, but also reveal the underlying principles that govern millions of years of evolution.

Despite the fact that the model was trained on just a fraction of yeast regulatory DNA in a few growth conditions, he’s impressed that it’s capable of making such useful predictions about the evolution of gene regulation in mammals.

“There are obvious near-term applications, such as the custom design of regulatory DNA for yeast in brewing, baking, and biotechnology,” he explains. “But extensions of this work could also help identify disease mutations in human regulatory DNA that are currently difficult to find and largely overlooked in the clinic. This work suggests there is a bright future for AI models of gene regulation trained on richer, more complex, and more diverse data sets.”

Even before the study was formally published, Vaishnav began receiving queries from other researchers hoping to use the model to devise non-coding DNA sequences for use in gene therapies.

“People have been studying regulatory evolution and fitness landscapes for decades now,” Vaishnav says. “I think our framework will go a long way in answering fundamental, open questions about the evolution and evolvability of gene regulatory DNA — and even help us design biological sequences for exciting new applications.”

Whitehead Institute

February 24, 2022

Whitehead Institute Director Ruth Lehmann has been awarded the 2022 Gruber Genetics Prize – one of the most prestigious recognitions in the field of genetics – along with fellow developmental biologists James Priess of the Fred Hutchinson Cancer Research Center and Geraldine Seydoux of the Johns Hopkins University School of Medicine.

The Prize was awarded for the trio’s independent, pioneering discoveries on the molecular mechanisms underlying the earliest stages of embryonic development. In announcing the award, the Gruber Foundation explained that, taken together, the scientists’ work has transformed the field of germ cell biology, uncovering answers to one of the most fundamental questions in genetics: how germ cells – the precursors of eggs and sperm – faithfully transmit genetic information across generations.

“As a result of their curiosity, innovation, and remarkable insights, each of these phenomenal scientists has played a pivotal role in unlocking the molecular mysteries of early embryonic development,” says Eric Olson, professor at UT Southwestern and member of the Gruber Prize selection advisory board. “It’s not an overstatement to say that their genetic findings regarding germ cells have helped to revolutionize modern developmental biology.”

“I am extraordinarily grateful to the Gruber Foundation for selecting me as a recipient of the Gruber Prize in Genetics,” says Lehmann, who is also a professor of biology at the Massachusetts Institute of Technology. “It is particularly delightful to share this award with James Preiss and Geraldine Seydoux, who are wonderfully insightful and creative scientists.

“I am also thrilled to be in the company of two Whitehead Institute colleagues who have received the Gruber Prize: Founding Member Rudolf Jaenisch, who won the inaugural Prize in 2001; and Founding Member and former Institute director Gerald Fink, who won it in 2010.”

Working primarily with the fruit fly Drosophila melanogaster, Lehmann made landmark discoveries regarding the composition, assembly and function of germplasm within the embryo. Her research has contributed to the first genetic framework for the specification of germ cell fate in any organism. She also helped uncover how oocyte mitochondria avoid transmitting mutations within their small genomes to offspring and how they associate with germplasm and primordial germ cells. Priess and Seydoux used a different model organism—the nematode Caenorhabditis elegans—in their research.

The Gruber Foundation established and awarded its first Genetics Prize in 2001. It was the world’s first major international prize devoted specifically to achievements in the realm of genetics research – and remains one of the most prestigious prizes in the field. It is awarded under the guidance of an international advisory board of distinguished scientists.

MIT senior Daniel Zhang aims to provide hope for young patients and support to young students.

Celina Zhao | Department of Biology

February 24, 2022

During the virtual spring 2020 semester, Daniel Zhang, a senior majoring in biology, put his time at home to good use. In the garage of his home in San Diego, California, Zhang helped his 13-year-old brother build a lab to study dry eye disease.

This combination of mentorship and medicine feels like second nature to Zhang. When his parents opened a family-run optometry clinic, Zhang was their first patient and then their receptionist. And after a close family member passed away from leukemia, he remembers thinking, “Humans are susceptible to so many diseases — why don’t we have better cures?”

That question propelled him to spend his high school summers studying biomarkers for the early detection of leukemia at the University of California at San Diego. He was invited to present his research at the London International Youth Science Forum, where he spoke to scientists from almost 70 countries. Afterward, he was hooked on the idea of scientific research as a career.

“Research is like standing on the shoulders of giants,” he says. “My experience at the forum was when I knew I loved science and wanted to continue using it to find common ground with others from completely different cultures and backgrounds.”

Exploring the forefront of cancer research

As soon as he arrived at MIT as a first-year undergraduate, Zhang began working under the guidance of postdoc Peter Westcott in professor Tyler Jacks’ lab. The lab focuses on developing better mouse and organoid models to study cancer progression — in Zhang’s case, metastatic colorectal cancer.

One of the ways to model colorectal cancer is by injecting an engineered virus directly into the colons of mice. The viruses, called lentiviral agents, “knock out” tumor suppressor genes and activate the so-called oncogenes that drive cancer forward. However, the imprecise nature of this injection also unintentionally transforms many “off-target” cells into cancer cells, producing a cancer that’s far too widespread and aggressive. Additionally, rare tumors called sarcomas are often initiated rather than adenocarcinomas, the type of tumor found in 95 percent of human cases. As a result, these mouse models are limited in their ability to accurately model colorectal cancer.

To address this problem, Zhang and Westcott designed a method using CRISPR/Cas9 to target a special stem cell called LGR5+, which researchers believe are the types of cells that, when mutated, grow into colorectal cancer. His technique modifies only the LGR5+ cells, which would allow researchers to control the rate at which adenocarcinomas grow. Therefore, it generates a model that is not only much more similar to human colorectal cancer than other models, but also allows researchers to quickly test for other potential cancer driver genes with CRISPR/Cas9. Designing an accurate model is crucial for developing and testing effective new therapies for patients, Zhang says.

During MIT’s virtual spring and fall semesters of 2020, Zhang shifted his focus from benchwork in the lab to computational biology. Using patient data from the Cancer Genome Atlas, Zhang analyzed mutation rates and discovered three genes potentially involved in colorectal cancer tumor suppression. He plans to test their function in his new mouse model to further validate how the dysfunction of these genes drives colorectal cancer progression.

For his work on organoid modeling of colorectal cancer, a third project he’s worked on during his time at the Jacks lab, he also won recognition from the American Association for Cancer Research (AACR). As one of 10 winners of the Undergraduate Scholar Award, he had the opportunity to present his research at the virtual AACR conference in 2021 and again at the next AACR Conference in New Orleans in April 2022.

He credits MIT’s “mens et manus” philosophy, encouraging the hands-on application of knowledge, as a large part of his early success in research.

“I’ve found that, at MIT, a lot of people are pursuing projects and asking questions that have never been thought of before,” Zhang says. “No one has ever been able to develop a late-stage model for colorectal cancer that’s amenable to gene editing. As far as I know, other than us, no one in the world is even working on this.”

Inspiring future generations to pursue STEM

Outside of the lab, Zhang devotes a substantial amount of time to sharing the science he’s so passionate about. Not only has he been awarded the Gene Brown Prize for undergraduate teaching for his time as a teaching assistant for the lab class 7.002 (Fundamentals of Experimental Molecular Biology), but he’s also taken on leadership roles in science outreach activities.

During the 2020-21 academic year, he served as co-director of DynaMIT, an outreach program that organizes a two-week STEM program over the summer for underserved sixth to ninth graders in the greater Boston area. Although the program is traditionally held in-person, in summer 2021 it was held virtually. But Zhang and the rest of the board didn’t let the virtual format deter them from maximizing the fun and interactive nature of the program. They packed and shipped nearly 120 science kits focused on five major topics — astronomy, biology, chemistry, mechanical engineering, and math — allowing the students to explore everything from paper rockets to catapults and trebuchets to homemade ice cream.

“At first, we were worried that most of the students wouldn’t turn on their cameras, since we saw that trend all over MIT classes during the semester,” Zhang says. “But almost everyone had their cameras on the entire time. It was really gratifying to see students come in on Monday really shy, but by Friday be actively participating, making jokes with the mentors, and being really excited about STEM.”

To investigate the long-term impacts of the program, he also helped kick-start netbet sports bettinga project that followed up with DynaMIT alumni, some of whom have already graduated from college. Zhang says: “We were happy to see that 80-90 percent of DynaMIT alumni enjoyed the program, rating it four or five out of five, and close to 70 percent of them said that DynaMIT had a really positive impact on their trajectory toward a career in STEM.”

Zhang has also served as president of the MIT Pre-medical Society, with the goals of fostering an encouraging environment for premed undergraduates, and providing guidance and resources to first- and second-year students still undecided about the premed path. To achieve these objectives, he pioneered an MIT-hosted mixer with the premedical societies of other Boston colleges, including Wellesley College, Boston University, Tufts University, and Harvard University. At the mixer, students were able to network with each other and listen to guest speakers from the different universities talk about their experiences in medicine. He also started a “big/little” initiative that paired third- and fourth-year mentors with first- and second-year students.

Providing new opportunity and hope

The wealth of activities Zhang has participated in at MIT has inspired his choices for the future. After graduation, he plans to take a gap year and work as a research technician in pediatric oncology before applying to MD/PhD programs.

On the mentorship side, he’s currently working to establish a nonprofit organization called Future African Scientist with his former Ugandan roommate, Martin Lubowa, whom he met at a study abroad program during MIT’s Independent Activities Period in 2020. The organization will teach high schoolers in Africa professional skills and expose them to different STEM topics — a project Zhang plans to work on post-MIT and into the long term.

Ultimately, he hopes to lead his own lab at the intersection of CRISPR-Cas9 technology and cancer biology, and to serve as a mentor to future generations of researchers and physicians.

As he puts it: “All of the experiences I’ve had so far have solidified my goal of conducting research that impacts patients, especially young ones. Being able to provide new opportunity and hope to patients suffering from late-stage metastatic diseases with no current cures is what inspires me every day.”

Alan Grossman to step down as head of the Department of Biology

Grossman led the biology community for eight years, increasing faculty diversity, support for outreach programs and graduate students.

School of Science

February 23, 2022

Alan D. Grossman, the Praecis Professor of Biology at MIT, has announced he will step down as the head of the Department of Biology before the start of the next academic year. He will continue to lead the department until the new head is selected. A search committee will convene later this spring to recommend candidates for Grossman’s successor.

“Alan Grossman is an outstanding biologist who is, and has been, deeply committed to the research and educational missions of the biology department,” says Nergis Mavalvala, the Curtis and Kathleen Marble Professor of Astrophysics and the dean of the MIT School of Science. “He has time and again established MIT biology as a leader in the life sciences at the Institute, in Kendall Square, and beyond.”

“It has been a privilege to lead this department and its talented members — faculty, staff, and students — for the past eight years,” says Grossman. “With the dedication and drive of this community, we have accomplished so much together and set new and ambitious goals for the future of life sciences research and education.”

Grossman was instrumental in securing a $50 million gift from Professor Emeritus Paul Schimmel PhD ’66 and his family to support life sciences across the Institute. Schimmel’s initial gift of $25 million established the Schimmel Family Program for Life Sciences that matched $25 million secured from other sources in support of the Department of Biology. The remaining $25 million from the Schimmel family will support the Schimmel Family Program in the form of matching funds.

“This transformative gift provides students with the resources they need to be successful in their education, research, and careers,” says Institute Professor Phillip A. Sharp, who also contributed to the matching gift. “Alan’s leadership and vision provided the framework to make this gift a reality for graduate students who perform life sciences research across the Institute, not just in biology.”

For many years, Grossman was deeply involved in graduate education. He served on the committees that oversee the graduate program in biology and the interdepartmental graduate program in computational and systems biology. For seven years, Grossman was director or co-director of the biology graduate program. He helped establish the interdepartmental graduate program in microbiology in 2007 and served as its founding director until 2012.

Before assuming the role as department head, Grossman also served the department as associate head and had served MIT on several committees, including as a member of the Committee on Curriculum and the Faculty Advisory Committee for the Office of Minority Education. Through the work of the department’s academic officers, student leaders, and advisors, Grossman oversaw the development of the most recent interdisciplinary undergraduate biology major, Course 5-7 (Chemistry and Biology).

Within his department, Grossman raised funds to endow support for students in the MIT Summer Research Program in Biology (MSRP-Biology). He worked with others to expand the diversity of the graduate program, the applicant pool for biology faculty positions, and the scientific workforce through a variety of outreach programs and endeavors.

Recently, Grossman raised additional funds to endow MSRP-Biology. Michael Gould and Sara Moss supplemented their initial gift in 2015 with an additional donation to further support, endow and rename MSRP-Biology to the Bernard S. and Sophie G. Gould MIT Summer Research Program in Biology to honor Gould’s parents.

“Sara and I are grateful for Alan’s nurturing of the program,” said Gould. “Without Alan, we never would have supported this wonderful program; and with Alan at the helm and Mandana Sassanfar as the director of outreach, we knew that many talented individuals would benefit from the research opportunities at MIT.”

Grossman’s tenure also saw the establishment of a cryo-electron microscopy (cryo-EM) facility at MIT. An anonymous donation of $5 million and a $2.5 million gift from the Arnold and Mabel Beckman Foundation supported the purchase of two cryo-electron microscopes that are housed in MIT.nano. These microscopes are used by life science researchers from many departments across MIT and throughout the Boston area.

“The existence of this facility has made it possible for MIT to recruit outstanding junior faculty members focused on using cryo-EM to address fundamental biological problems,” says associate department head Professor Jacqueline Lees. “At a more general level, Alan has been remarkably successful at junior faculty recruitment and in increasing the diversity of our faculty.”

During Grossman’s tenure as department head and in collaboration with the MIT-affiliated life sciences institutes and the hard work of search committees, the department has hired more than 20 faculty members, over than half of whom are women and/or from groups underrepresented in STEM. This faculty renewal involved forging a relationship with the Ragon Institute of MGH, MIT, and Harvard and includes three new faculty members located at the Ragon Institute. With the influx of new faculty members, the department’s senior faculty instituted a robust plan for mentoring junior faculty, supplementing programs that are offered at the school and Institute levels.

In his own research, Grossman combines a range of approaches — genetic, molecular, physiological, biochemical, cell-biological, and genomic — to study fundamental biological processes in bacteria. His current work is focused mechanisms controlling horizontal gene transfer, the process by which bacteria move genes from one organism to another, the primary means by which antibiotic resistances are spread among bacteria.

Grossman received a BA in biochemistry from Brown University in 1979, and a PhD in molecular biology from the University of Wisconsin at Madison in 1984. After a postdoctoral fellowship in the Department of Cellular and Developmental Biology at Harvard University, Grossman joined MIT’s Department of Biology in 1988. He is a fellow of the American Academy of Arts and Sciences, the American Academy of Microbiology, and is a member of the National Academy of Sciences. He received a life-saving heart transplant in 2006.

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