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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.”

The model remodeler

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. These 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.

From bench to biotech

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 despite 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.”

Whitehead Institute director Ruth Lehmann receives the 2022 Gruber Genetics Prize
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.

Mentorship and medicine

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 a 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.

Advocating for vaccine equity

Postdoc Dig Bijay Mahat became a cancer researcher to improve healthcare in Nepal, but the COVID-19 pandemic exposed additional resource disparities.

Raleigh McElvery
February 17, 2022

When Dig Bijay Mahat arrived at MIT in 2017 to begin his postdoctoral studies, he had one very clear goal: to become an expert in cancer research and diagnostics so he could improve healthcare in Nepal, where he was born. In 2020, when the COVID-19 pandemic laid bare additional discrepancies in resource equity around the world, his goal did not waiver. But it did expand to fill a more immediate need — help Nepal find the best way to navigate widespread COVID testing requirements and vaccine rollouts.

Mahat was born in the western region of Nepal, where his family has owned a large swath of land for generations. Before Mahat was born, his grandfather passed away unexpectedly. And, as the eldest son, Mahat’s father assumed responsibility for his five of siblings at the age of 21. As a result, Mahat’s father missed his chance to pursue the education he’d envisioned. Perhaps because of this, he made it his mission to give Mahat the education he never received. However, no school was quite good enough, and he shuffled Mahat between nine different institutions before the age of 18.

While his father wished him all the success and prestige that would come with pursing a medical career, Mahat had other plans. Toward the end of high school, he became captivated by song writing, and even secretly used his school tuition money one semester to record an album. “It was a disastrous flop,” he now recalls with a smile.

Although his foray into the music industry provides comic relief today, at the time Mahat was dismayed to be back on the medical track. However, he did convince his father to let him go to the US for college. He ended up at Towson University in Maryland, living with his aunt and uncle and delivering pizzas to support his nuclear family back in Nepal. Some weeks, he clocked in over 100 hours of deliveries.

As a molecular biology, biochemistry, and bioinformatics major, he took every research opportunity he could get, and became enthralled by breast cancer research. Shortly thereafter, his mother was diagnosed with the same disease, which further strengthened his conviction to learn as much as he could in the US, and return to Nepal to help as many patients as he could.

“The state of cancer diagnostics is very poor in Nepal,” he explains. Patient biopsies must be sent to other countries such as India — a costly practice at the mercy of politics and travel restrictions. “The least we can do is become self-sufficient and provide these vital molecular diagnostics tools to our own people,” Mahat says.

He went on to earn his PhD in molecular biology and genetics from Cornell University, and by the fall of 2017 he had secured his dream job: a postdoctoral position in the lab of MIT Professor of Biology Susan Lindquist. Mahat had spent much of his time at Cornell studying a protein known as heat shock factor 1, and Lindquist had conducted seminal work showing that this same protein enables healthy cells to suddenly turn into cancer cells. Just as he had finalized his new apartment lease and was preparing to start his new job, Lindquist wrote from the hospital to tell him she had late-stage ovarian cancer, and suggested he complete his postdoctoral studies elsewhere.

Gutted, he scrambled to find another position, and built up the courage to contact MIT professor, Koch Institute member, and Nobel laureate Phil Sharp. Mahat put together a formal research proposal and presented it to Sharp. A few days later, he became the lab’s newest member.

“From the beginning, the things that struck me about Phil were his humility, his attention to experimental detail, and his inexplicable reservoir of insight,” Mahat says. “If I could carry even just some of that same humility with me for the rest of my life, I would be a good human being.”

In 2018, Mahat and Sharp filed a patent with the potential to revolutionize disease diagnostics. Widely-available single-cell sequencing technologies reveal the subset of RNAs inside a cell that build proteins. But Mahat and his colleagues found a way to take a snapshot of all the RNA inside a single cell that is being transcribed from DNA — including RNAs that will never become proteins. Because many ailments arise from mutations in the “non-coding” DNA that gives rise to this “non-coding” RNA, the researchers hope their new method will help expose the function of non-coding variants in diseases like diabetes, autoimmune disorders, neurological diseases, and cancer.

Mahat was still immersed in this research in early 2020 when the COVID-19 pandemic began to escalate. As case numbers soared around the world, it became clear to him that the wealth of COVID testing resources available on MIT’s campus — and throughout the US in general — dwarfed the means available to his family back in Nepal. Polymerase chain reaction (PCR) testing remains the most popular and accurate means to detect the virus in patient samples. While PCR machines are quite common in molecular biology labs across the US, the entire country of Nepal owned just a few at the start of the pandemic, according to Mahat.

“Digbijay was focused intensely on developing our novel single-cell technology when he became aware of Nepal’s challenges to control the COVID-19 pandemic,” Sharp recalls. “While continuing his research in the lab, he spent several months contacting leaders in pharmaceutical companies in the US and leaders in public health in Nepal to help arrange access to vaccines and rapid tests.”

Mahat was already in contact with the Nepali Ministry of Health and Population regarding the state of the country’s cancer diagnostics, and so the government called on him to advise their COVID testing efforts. Given the high cost and limited availability of PCR machines and reagents, Mahat began discussions with MIT spinoff Sherlock Biosciences, in order to bring an alternative testing technology to Nepal. These COVID tests, which were developed at the Broad Institute of MIT and Harvard, use the CRISPR/Cas9 system — rather than PCR — to detect the SARS-CoV2 virus that causes COVID-19, making them cheaper and more readily available. Sherlock Biosciences ultimately donated $100,000-worth of testing kits, supplemented by an additional $100,000 grant from the Open Philanthropy Project to help purchase the equipment necessary to implement the tests. In December of 2020, Mahat and his wife Rupa Shah flew to Nepal to set up a testing center using these new resources.

Although this required Mahat to briefly pause his MIT research, Sharp was supportive of these extracurricular pursuits. “We are very proud of Jay’s effective work benefiting the people of Nepal,” Sharp says.

Around the same time, Mahat reached out to Institute professor and Moderna co-founder Robert Langer to help initiate vaccine talks with the Nepali government. Through Sharp’s contacts, Mahat was also able to connect the government with Johnson & Johnson. In addition, Mahat, Sharp, and Emeritus Professor Uttam RajBhandary wrote a letter to MIT president Rafael Reif, who joined other university leadership in urging the Biden administration to donate vaccines to low-income countries.

Nepal ultimately received its COVID-19 vaccines through the COVAX program, co-led by the Coalition for Epidemic Preparedness Innovations, GAVI Alliance, and the World Health Organization. Today, the country has begun administering boosters. There were also some funds left over from the Open Philanthropy Project grant, which went toward sending Nepal several thousand PCR kits designed to distinguish between the delta and omicron variants. Professor Tyler Jacks, the Koch Institute director at that time, also connected Mahat with the company Thermo Fisher Scientific to secure additional PCR reagents.

Roshan Pokhrel, the Secretary of Nepal’s Ministry of Health and Population, met Mahat prior to the pandemic, and relied on his expertise to begin establishing Nepal’s National Cancer Institute (NCI) in 2020. “It was his cooperation and coordination that helped us set up NCI,” Pokhrel says. “Mr. Mahat’s continuous support during the first two waves of our COVID-19 vaccine distribution was also highly appreciated. During the recent omicron outbreak, his support in our public laboratory helped us to monitor the variant.”

Bhagawan Koirala, chairman of the Nepal Medical Council, participated in the vaccine talks that Mahat organized between Nepal’s Ministry of Health and Johnson & Johnson. Koirala says he was impressed by Mahat’s exceptional credentials and his modesty, as well as his desire to promote cancer research and diagnostics. As the chairman of the Kathmandu Institute of Child Health, Koirala hopes to engage Mahat’s expertise in the future to help advance pediatric cancer research in Nepal.

“We have spoken extensively about the policies regarding cancer diagnostics in Nepal,” Koirala says. “Dr. Mahat and I are eager to work with the government to introduce policies that will help develop local diagnostic capacity and discourage sending patient samples out of the country. This will save costs, ensure patient privacy, and improve quality of care and research.”

These days, Mahat is nothing short of a local celebrity in Nepal. Despite his current drive for ensuring vaccine equity, his ultimate goal is still to work with individuals like Koirala and Pokhrel to bring cancer treatment resources to the country. He not only envisions setting up his own research center there, but also inspiring young people to pursue careers in research. “Before me, no one in my entire village had pursued a scientific career, so if I could motivate even a few young kids to follow that path, it would be a win for me.”

But, he adds, he’s not ready to leave MIT just yet; he still has more to learn. “I feel privileged and honored to be part of this compassionate community,” he says. “I’m also proud — proud that we’ve been able to come together in this time of need.”

Sometimes science takes a village
Greta Friar | Whitehead Institute
February 17, 2022

Alexandra Navarro, a graduate student in Whitehead Institute Member Iain Cheeseman’s lab, was studying the gene for CENPR, a protein related to cell division—the Cheeseman lab’s research focus—when she came across something interesting: another molecule hidden in CENPR’s genetic code. The hidden molecule is a peptide only 37 amino acids long, too small to show up in most surveys of the cell. It gets created only when the genetic code for CENPR is translated from an offset start and stopping place—essentially, when a cell reads the instructions for making CENPR in a different way. The Cheeseman lab has become very interested in these sorts of hidden molecules, which they have found lurking in a number of other molecules’ genetic codes. Navarro began studying the peptide as a side project during slow periods in her main research on cell division proteins. However, as her research on the peptide progressed, Navarro eventually found herself unsure of how to proceed. CENPR belongs in the centromere, a part of the cell necessary for cell division, but the alternative peptide ends up in the Golgi, a structure that helps to modify molecules and prep them for delivery to different destinations. In other words, the peptide had nothing to do with the part of the cell that Navarro and Cheeseman typically study.

Usually when Navarro comes across something outside of her area of expertise, she will consult with her lab mates, others in Whitehead Institute, or nearby collaborators. However, none of her usual collaborators’ research focuses on the Golgi, so this time Cheeseman suggested that Navarro share what they had found and ask for input from as wide a circle of researchers as possible—on the internet. Often, researchers guard their work in progress carefully, reluctant to share it lest they be scooped, which means someone else publishes a paper on the same topic first. In the competitive world of academic research, where publishing papers is a key part of getting jobs, tenure, and future funding, the specter of scooping can loom large. But science is also an inherently collaborative practice, with scientists contributing droplets of discovery to a shared pool of knowledge, so that new findings can be built upon what came before. Cheeseman is a board member of ASAPbio (Accelerating Science and Publication in biology), a nonprofit that promotes open communication, the use of preprints, and transparent peer review in the life sciences. Researchers like Cheeseman believe that if science adopts more transparent and collaborative practices, such as more frequently and widely sharing research in progress, this will benefit both the people involved and the quality of the science, and will speed up the search for discoveries with the potential to positively impact humankind. But how helpful are such “open science” practices in reality? Navarro and Cheeseman had the perfect opportunity to find out.

The power of preprints

Navarro and Cheeseman wrote up what they knew so far–they had found a hidden peptide that localizes exclusively to the Golgi, and it stays there throughout the cell cycle–as a “preprint in progress,” an incomplete draft of a paper that acknowledges there is more to come. In December 2020, they posted the preprint in progress to bioRxiv, a website that serves as a repository for biology preprints, or papers that have not yet

been published. The site was inspired by arXiv, a similar repository launched in 1991 to provide free and easy access to research in math, physics, computer science, and similar fields. arXiv has become a central hub for research in these fields, with an average of 10-15,000 submissions and 30 million downloads per month. The biology fields were slower to create such a hub: BioRxiv launched in 2013. In December, 2021, it received around 3,000 submissions and 2.3 million downloads.

Navarro and Cheeseman’s decision to post a preprint in progress to bioRvix is not common practice, but a lot of researchers have started posting preprints that resemble the final paper closer to publication. Some journals even require it. This type of early sharing has many benefits: contrary to the fear that sharing research before publication will lead to scooping, it allows researchers to stake a claim sooner by making their work public record pre-publication. Preprints enable researchers to show off their most current work during the narrow windows of the academic job cycle. This can be particularly crucial for early career researchers whose biggest project to date—such as graduate thesis work—is still in publication limbo. Preprints also allow new ideas and knowledge to get out into the world sooner, the better to inspire other researchers. Findings that seemed minor at first have provided the key insight for someone else’s major discovery throughout biology’s history. The sooner research is shared, the sooner it can be built upon to develop important advances, like new medicines or a better model of how a disease spreads.

Navarro and Cheeseman weren’t expecting their discovery to have that kind of major impact, but they knew the peptide could be useful to researchers studying the Golgi. The peptide is small and doesn’t disrupt any functions in the cell. Researchers can attach fluorescent proteins to it that make the Golgi glow in imaging. These traits make the peptide a useful potential tool. Since Navarro and Cheeseman posted the preprint, multiple researchers have reached out about using the peptide.

However, the main goal of posting a preprint in progress, as opposed to a polished preprint, is to ask for input to further the research. The morning after the researchers put their preprint on bioRxiv, Cheeseman shared it on Twitter and asked for feedback. Other researchers soon shared the tweet further, and responses started flooding in. Some researchers simply commented that they found the project interesting, which was reassuring for Cheeseman and Navarro.

“It was nice to see that we weren’t the only ones who thought this thing we found was really cool,” Navarro says. “It gave me a lot of motivation to keep moving on with this project.”

Then, some researchers had specific questions and ideas. The topic that seemed of greatest interest was how the peptide ends up at the Golgi, followed by where exactly in the Golgi it ends up. Researchers suggested online tools that might help predict answers to these questions. They proposed different mechanisms that might be involved.

Navarro used these suggestions to design a new series of experiments, in order to better characterize how the peptide associates with the Golgi. She found out that the peptide attaches to the Golgi’s outer-facing membrane. She started developing an understanding of which of peptide’s 37 amino acids were necessary for Golgi localization, and so was able to narrow in on a 14-amino acid sequence within the peptide that was sufficient for this localization.

Her next question was what specific mechanisms were driving the peptide’s Golgi localization. Navarro had a good lead for one mechanism: the evidence and outside input suggested that after the peptide was created, it likely underwent a modification that gave it a sticky tag to anchor it to the Golgi. What would be the best experiments to confirm this mechanism and determine the other mechanisms involved? Navarro and Cheeseman decided it was time to check back in with the crowd online.

Narrowing in on answers

Navarro and Cheeseman updated their preprint with their new findings, and invited further feedback. This time, they had a specific ask: how to test whether the peptide has the modification they suspected. They received suggestions: a probe, an inhibitor. They also received some unexpected feedback that took them in a new direction. Harmit Malik, professor and associate director of the basic sciences division at Fred Hutch, studies the evolutionary changes that occur in genes. Malik found the peptide interesting enough to dig into its evolutionary history across primates. He emailed Cheeseman and Navarro his findings. Versions of the peptide existed in many primates, and some of the variations between species affected where the peptide ended up. This was a rich new vein of inquiry for Navarro to follow in order to pinpoint exactly which parts of the sequence were necessary for Golgi localization, and the researchers might never have come across it if they had not sought input online.

Guided by the latest set of suggestions, Navarro resumed work on the project. She found evidence that the peptide does undergo the suspected modification. She winnowed down to a 10-amino acid sequence within the peptide that appears to be the minimal sequence necessary for this type of Golgi localization. Navarro and Cheeseman rewrote the paper, adding the discovery of a minimal Golgi targeting sequence—basically a postal code that marks a molecule’s destination as the Golgi. They posted a third version of the preprint in September, 2021. This time, Cheeseman did not ask Twitter for feedback: the paper may undergo more changes, but it now contains a complete research story.

The changing face of science

Based on their experience, would Cheeseman and Navarro recommend sharing preprints in progress? The answer is a resounding yes—if the project is a good fit. Both agree that for projects like this, where the subject is outside the expertise of a researcher’s usual circle of collaborators, asking the wider scientific community for help can be extremely valuable.

“I often share my research with other people at Whitehead Institute, and other cell division researchers at conferences, but this process allowed me to share it with people who work in different scientific areas, with whom I would not normally engage,” Navarro says.

Cheeseman hopes that sharing hubs like bioRxiv will develop ways for even larger and more diverse groups of scientists to connect.

If researchers are hesitant to use an open science approach, Cheeseman and Navarro recommend testing the waters by starting with a lower stakes project. In this case, Navarro’s Golgi paper was a side project, something of personal interest but not integral to her career. Having had a positive experience using an open approach on this project, Cheeseman and Navarro agree they would be comfortable using such an approach again in the future.

“I wouldn’t suggest sharing a preprint in progress for every paper, but I think constructive opportunities are more plentiful than researchers may realize,” Cheeseman says.

In general, Cheeseman thinks, the biology field needs to re-envision how its science gets shared.

“The idea that one size fits all, that everything needs to be a multi-figure paper in a high impact journal, is just not compatible with the way that people do research,” Cheeseman says. “We need to get flexible and explore and value scholarship in every form.”

As for the peptide paper? Regardless of where it ends up, Cheeseman and Navarro consider their open science experiment a success. By sharing their research and asking for input, they gained insights, research tools, and points of view that took the project from a curious finding to a rich understanding of the mechanisms behind Golgi localization. Their early realization that the peptide functions outside of their region of expertise could have been a dead end. But by being open about what they were working on and what sort of guidance they needed, the researchers were able to overcome that hurdle and decode their mystery peptide, with a little help from the wider scientific community.

Seven new faculty join the MIT School of Science

Departments of Biology and Brain and Cognitive Sciences welcome new professors.

School of Science
February 16, 2022

This winter, seven new faculty members join the MIT School of Science in the departments of Biology and Brain and Cognitive Sciences.

Siniša Hrvatin studies how animals initiate, regulate, and survive states of stasis, such as torpor and hibernation. To survive extreme environments, many animals have evolved the ability to decrease metabolic rate and body temperature and enter dormant states. His long-term goal is to harness the potential of these biological adaptations to advance medicine. Previously, he identified the neurons that regulate mouse torpor and established a platform for the development of cell-type-specific viral drivers.

Hrvatin earned his bachelor’s degree in biochemical sciences in 2007 and his PhD in stem cell and regenerative medicine in 2013, both from Harvard University. He was then a postdoc in bioengineering at MIT and a postdoc in neurobiology at Harvard Medical School. Hrvatin returns to MIT as an assistant professor of biology and a member of the Whitehead Institute for Biomedical Research.

Sara Prescott investigates how sensory inputs from within the body control mammalian physiology and behavior. Specifically, she uses mammalian airways as a model system to explore how the cells that line the surface of the body communicate with parts of the nervous system. For example, what mechanisms elicit a reflexive cough? Prescott’s research considers the critical questions of how airway insults are detected, encoded, and adapted to mammalian airways with the ultimate goal of providing new ways to treat autonomic dysfunction.

Prescott earned her bachelor’s degree in molecular biology from Princeton University in 2008 followed by her PhD in developmental biology from Stanford University in 2016. Prior to joining MIT, she was a postdoc at Harvard Medical School and Howard Hughes Medical Institute. The Department of Biology welcomes Prescott as an assistant professor.

Alison Ringel is a T-cell immunologist with a background in biochemistry, biophysics, and structural biology. She investigates how environmental factors such as aging, metabolism, and diet impact tumor progress and the immune responses that cause tumor control. By mapping the environment around a tumor on a cellular level, she seeks to gain a molecular understanding of cancer risk factors.

Ringel received a bachelor’s degree in molecular biology, biochemistry, and physics from Wesleyan University, then a PhD in molecular biophysics from John Hopkins University School of Medicine. Previously, Ringel was a postdoc in the Department of Cell Biology at Harvard Medical School. She joins MIT as an assistant professor in the Department of Biology and a core member of the Ragon Institute of MGH, MIT and Harvard.

Francisco J. Sánchez-Rivera PhD ’16 investigates genetic variation with a focus on cancer. He integrates genome engineering technologies, genetically-engineered mouse models (GEMMs), and single cell lineage tracing and omics approaches in order to understand the mechanics of cancer development and evolution. With state-of-the-art technologies — including a CRISPR-based genome editing system he developed as a graduate student at MIT — he hopes to make discoveries in cancer genetics that will shed light on disease progression and pave the way for better therapeutic treatments.

Sánchez-Rivera received his bachelor’s degree in microbiology from the University of Puerto Rico at Mayagüez followed by a PhD in biology from MIT. He then pursued postdoctoral studies at Memorial Sloan Kettering Cancer Center supported by a HHMI Hanna Gray Fellowship. Sánchez-Rivera returns to MIT as an assistant professor in the Department of Biology and a member of the Koch Institute for Integrative Cancer Research at MIT.

Nidhi Seethapathi builds predictive models to help understand human movement with a combination of theory, computational modeling, and experiments. Her research focuses on understanding the objectives that govern movement decisions, the strategies used to execute movement, and how new movements are learned. By studying movement in real-world contexts using creative approaches, Seethapathi aims to make discoveries and develop tools that could improve neuromotor rehabilitation.

Seethapathi earned her bachelor’s degree in mechanical engineering from the Veermata Jijabai Technological Institute followed by her PhD in mechanical engineering from Ohio State University. In 2018, she continued to the University of Pennsylvania where she was a postdoc. She joins MIT as an assistant professor in the Department of Brain and Cognitive Sciences with a shared appointment in the Department of Electrical Engineering and Computer Science at the MIT Schwarzman College of Computing.

Hernandez Moura Silva researches how the immune system supports tissue physiology. Silva focuses on macrophages, a type of immune cell involved in tissue homeostasis. He plans to establish new strategies to explore the effects and mechanisms of such immune-related pathways, his research ultimately leading to the development of therapeutic approaches to treat human diseases.

Silva earned a bachelor’s degree in biological sciences and a master’s degree in molecular biology from the University of Brasilia. He continued to complete a PhD in immunology at the University of São Paulo School of Medicine: Heart Institute. Most recently, he acted as the Bernard Levine Postdoctoral Fellow in immunology and immuno-metabolism at the New York University School of Medicine: Skirball Institute of Biomolecular Medicine. Silva joins MIT as an assistant professor in the Department of Biology and a core member of the Ragon Institute.

Yadira Soto-Feliciano PhD ’16 studies chromatin — the complex of DNA and proteins that make up chromosomes. She combines cancer biology and epigenetics to understand how certain proteins affect gene expression and, in turn, how they impact the development of cancer and other diseases. In decoding the chemical language of chromatin, Soto-Feliciano pursues a basic understanding of gene regulation that could improve the clinical management of diseases associated with their dysfunction.

Soto-Feliciano received her bachelor’s degree in chemistry from the University of Puerto Rico at Mayagüez followed by a PhD in biology from MIT, where she was also a research fellow with the Koch Institute. Most recently, she was the Damon Runyon-Sohn Pediatric Cancer Postdoctoral Fellow at The Rockefeller University. Soto-Feliciano returns to MIT as an assistant professor in the Department of Biology and a member of the Koch Institute.

Whitehead Institute Member Pulin Li named an Allen Distinguished Investigator
Merrill Meadow | Whitehead Institute
February 9, 2022

Whitehead Institute Member Pulin Li has been selected by The Paul G. Allen Frontiers Group to be an Allen Distinguished Investigator. The Allen Distinguished Investigator program backs creative, early-stage research projects in biology and medical research that would not otherwise be supported by traditional research funding programs. Each Allen Distinguished Investigator award provides three years of research funding.

Li, who is also an assistant professor of biology and the Eugene Bell Career Development Professor of Tissue Engineering at Massachusetts Institute of Technology, studies how circuits of genes within individual cells enable multicellular functions and phenomena such as the patterns of varied cell types that comprise a tissue. Her lab combines approaches from synthetic biology, developmental biology, biophysics, and systems biology to quantitatively understand how cells communicate to produce those phenomena. The work could lead to ways to program stem cells to form tissues for regenerative medicine.

“I am very grateful for this generous support ,” Li says. “The Frontiers Group’s commitment to early-stage investigations is welcome by scientists who are trying to open new paths to discovery.”

Li’s project seeks to advance the field of synthetic developmental biology through improving the process researchers use to create small groups of cells that develop certain functions of organs. Known as organoids, these tissues enable researchers to learn more about how organs develop and function in both healthy and diseased states; and they could be used for rapid and accurate preclinical drug testing.

“All organs in our body are ecosystems of different cell types that constantly talk to each other and regulate each other’s fates, and the challenge researchers face is creating organoids that reflect this multifaceted interaction,” Li explains. “Organoids that include a more complex and complete suite of tissues may prove to function more like real organs. In the project supported by the Allen Distinguished Investigator award, my lab seeks to improve the development of organoids by introducing a type of supportive tissue known as the stroma.”

Most organs are made of epithelial cells juxtaposed with the stroma’s connective tissue. Within the stroma, mesenchymal cells help to orchestrate tissue formation and the spatial organization of other cell types. The versatile function of mesenchymal cells critically depends on their extraordinary capability to produce an array of molecules that can stimulate other cell types.

As a result, each population of mesenchymal cells has distinct capability to support the development of other cell types, control organ shapes, respond to tissue injury, and regulate inflammation.

“Despite the important function of mesenchymal cells,” Li says, “they are mostly missing in the organoids that researchers have thus far developed. Our goal is to engineer diverse populations of human mesenchymal cells and  reconstitute their spatial relationship and communication with other cell types in the stroma.

“Ultimately, we believe, these synthetically engineered stroma will help unleash the full potential of organoids as useful tools for studying organ formation and physiology.”

The Paul G. Allen Frontiers Group was founded in 2016 by the late philanthropist Paul G. Allen to explore the landscape of bioscience and to identify and foster ideas that will change the world. Its Allen Distinguished Investigators program advances frontier explorations with exceptional creativity and potential impact.