Category: Faculty Locations

MIT Professor Susumu Tonegawa, renowned molecular biologist and Nobel laureate, dies at 86

Tonegawa made landmark discoveries about how the immune system generates antibody diversity and how the brain forms memories.

Anne Trafton | MIT News
July 15, 2026

Susumu Tonegawa, the Picower Professor of Biology and Neuroscience at MIT and a Nobel laureate, died July 11 at the age of 86.

Tonegawa was a renowned molecular biologist who wielded his keen insight in a variety of fields, including immunology and neuroscience. In the early 1980s, Tonegawa discovered how the immune system generates its incredible diversity of antibodies — a breakthrough that earned him the Nobel Prize in Physiology or Medicine in 1987.

Following that landmark achievement, he turned his attention to neuroscience, where his work has helped to reveal how the brain stores memories as traces called “engrams.”

An MIT faculty member for more than 40 years, Tonegawa also served as the founding director of MIT’s Picower Institute for Learning and Memory and director of the RIKEN Brain Science Institute of Japan, and was a Howard Hughes Medical Institute Investigator.

“Few scientists have reshaped our understanding of biology as profoundly as Susumu Tonegawa,” says Myriam Heiman, director of the Picower Institute. “His intellectual fearlessness, extraordinary creativity, and relentless pursuit of fundamental questions opened entirely new frontiers in both immunology and neuroscience. His influence on science and on the people who had the privilege of working alongside him is immeasurable.”

Drawn to molecular biology

Born in Nagoya, Japan, Tonegawa spent his early years moving between rural towns, due to his father’s job as an engineer for a textile company. When it was time for him to go to high school, his parents sent him to a school in Tokyo, where he became interested in chemistry.

He was admitted to the University of Kyoto to study chemistry, and while there, he was drawn to the nascent field of molecular biology. He began his graduate studies at the Institute for Virus Research at the University of Kyoto, but after only a couple of months, his advisor, Professor Itaru Watanabe, suggested that he apply to a school in the United States, which had more advanced molecular biology programs.

Tonegawa took that advice and was accepted at the University of California at San Diego, where he studied how a virus called phage lambda controls gene transcription. After earning his PhD in 1968, he went on to a postdoc in a lab at the Salk Institute.

In that lab, Tonegawa began studying gene expression of a virus known as SV40. However, his U.S. visa was set to expire at the end of 1970, so he soon headed for a position at the newly established Basel Institute for Immunology in Switzerland.

At the time, Tonegawa had little background in immunology, but he soon became fascinated by the 100-year-old question of “antibody diversity” — how the body’s immune system is able to generate hundreds of millions of antibodies from a relatively small set of genes. (The entire human genome contains about 20,000 genes.) That antibody diversity is what allows the immune system to recognize so many pathogens, including those it has never seen before.

With colleagues in Basel, Tonegawa discovered that each antibody protein is not encoded by its own gene — instead, genes for different components of the antibody can be randomly recombined to generate limitless combinations.

In 1987, Tonegawa was a solo recipient of the Nobel Prize for discovering that process, known as V(D)J gene rearrangement. In announcing the award, the Nobel committee noted that Tonegawa’s discoveries “explain the genetic background allowing the enormous richness of variation amongst antibodies. Beyond deeper knowledge of the basic structure of the immune system these discoveries will have importance in improving immunological therapy of different kinds, such as for instance the enforcement of vaccinations and inhibition of reactions during transplantation.”

From antibodies to engrams

In the early 1980s, after his groundbreaking antibody discoveries, Tonegawa began to feel the urge to turn to new research directions. He also wanted to return to the United States, so in 1981, he accepted the offer of a professorship at MIT’s Center for Cancer Research (today known as the Koch Institute for Integrative Cancer Research). There, he began working on T cells and contributed to scientists’ understanding of how T cells are able to generate a large diversity of T-cell receptors.

While at the CCR, he also began to study questions in neuroscience. As he told an interviewer from the Picower Institute in 2022, he was always in search of new scientific endeavors to keep him interested in his work.

“When I decided to become a scientist, my criteria of what to do was whether the scientific problem I got to solve was interesting or not. Whether I’m curious our not. I didn’t think about other things like, Could it be too risky? Can I really develop my career by venturing into the field I am not familiar with? That never occurred to me. I just followed my curiosity and instinct,” Tonegawa said in an interview published in the summer 2022 Picower Institute newsletter.

In 1994, he was chosen as the founding director for MIT’s Center for Learning and Memory, which became the Picower Institute for Learning and Memory in 2002. Tonegawa continued to serve as the center’s director until the end of 2006.

Professor Li-Huei Tsai, who succeeded Tonegawa as the Picower Institute’s director, calls working alongside Tonegawa “one of the greatest honors of my career.”

“His passion, boundless energy, and unwavering pursuit of the fundamental mechanisms underlying memory were contagious, inspiring generations of neuroscientists to join and advance the field. Today, we lost a giant. His scientific legacy will continue to shape neuroscience for years to come, and he will be deeply missed by all of us,” she says.

Over the past two decades, Tonegawa’s lab has made significant discoveries in the field of memory research. In 2013, he and his colleagues reported that they had identified “engrams” in the brain’s hippocampus. These engrams consist of episodic memories — memories of experiences — that are stored in specific groups of hippocampal cells. Engrams encode elements including objects, space, and time, linked to a specific experience.

At that time, the researchers also found that it was possible to implant “false memories” in mice by using optogenetics to reactivate an existing engram while the animals formed a new memory. This prompted the mice to associate a new location with the memory of an event that had actually happened in a different location.

Later work from Tonegawa’s lab showed that engrams extend beyond the hippocampus and are stored across a widely distributed complex that spans many brain circuits. More recently, he had been working on engrams of “knowledge memory” to decipher the fundamental mechanism of abstract memory. His recent work also delved into how the emotional associations of memories are encoded, and how the brain maintains a timeline of chronological events.

In addition to the Nobel Prize, Tonegawa received many other awards, including the Albert and Mary Lasker Award for Basic Research in 1987, the Bristol-Myers Award for Distinguished Achievement in Cancer Research in 1986, and the David M. Bonner Lifetime Achievement Award from the University of California at San Diego in 2010. He was also known for training many scientists who are now leaders in the field of neuroscience.

Tonegawa was a longtime fan of the Boston Red Sox, and in May 2004, he had the opportunity to throw out the ceremonial first pitch at Fenway Park, as part of the team’s tribute to the Boston area’s scientific and medical communities.

He is survived by his wife, Mayumi Tonegawa ’92, two children, Hidde Tonegawa ’09 and Hanna Tonegawa, and two grandchildren. He was predeceased by a son, Satto Tonegawa.

Following a private funeral, his ashes will be buried in Kyoto, Japan.

Why are some bacterial genes high in purines?

In certain species of bacteria, the answer lies in shielding RNA transcripts from a quality-control factor called Rho. Understanding the requirements for expressible sequences is critical for expression engineering of therapeutic agents.

Lillian Eden | Department of Biology
July 2, 2026

In the study of bacteria, a longstanding dogma held that two molecular machines — RNA polymerase, which leads the way in transcribing DNA into RNA, and ribosomes, which bring up the rear translating RNA into proteins — worked so closely in tandem that they were effectively attached.

This close coupling of transcription and translation in bacteria was thought to be fundamental to gene expression in part because the trailing ribosome could shield nascent gene products from an effective and omnipresent quality-control protein called Rho.

In bacteria that exhibit something called runaway transcription, however, the polymerase instead speeds ahead, unhitched from its protective ribosome. Inexplicably, however, in bacteria that exhibit this runaway transcription, such as Bacillus subtilis, Rho targeted primarily noncoding, useless RNA products.

New research from the Department of Biology reveals that the secret to Rho’s quality-control specificity lies in the sequence composition of nucleotide bases that make up coding strands of DNA.

“We started with a hypothesis that Rho was regulated by sequence, but the fact that the sequence alone was enough to protect any gene in the entire B. subtilis genome from Rho was really surprising,” says Julia Dierksheide PhD ’26, a graduate student in the Li Lab and first author of a paper recently published in Nature Microbiology. “That’s a really diverse range of sequences — what sequence feature is shared by every single gene in the genome?”

Barricading with bias

Rho serves as a termination factor, meaning that it is a crucial mechanism for preventing bacteria from wasting precious resources by making RNA transcripts that serve no purpose.

All the information a bacterial cell needs is encoded in its DNA, which is made up of two strands of nucleic acids. These strands twist together to form a double helix, with genetic information codified in pairs of bases: purines guanine and adenine are matched with pyrimidines cytosine and thymine, respectively. Any sequence that gives rise to RNA transcripts is stored in complement to a parallel, noncoding strand, meaning that a large portion of genetic material is transcriptionally useless.

Coding DNA strands in certain bacteria were known to be significantly higher in purines guanine and adenine compared to the rest of the bacterial genome. The researchers found that this purine bias alone shields productive mRNA transcripts from Rho-mediated termination.

“I love having a big, complicated dataset and trying to reduce that to biological meaning,” Dierksheide says. “It seems like Rho itself has been broadly shaping the evolution of the B. subtilis genome to create these sequence composition biases.”

Bacterial species that, over generations, have lost Rho no longer exhibit this strong purine bias.

Rho also serves as a regulatory factor in bacteria becoming motile, forming biofilms, or sporulating, all of which are critical for biology and survival. The purine bias could also provide a layer of protection against the insertion of foreign DNA, for example, when a viral bacteriophage infects bacteria.

“Bacteria exist as single cells, so everything that they do, they have to do through gene expression,” Dierksheide says. “Understanding the fundamental details about how gene expression works, how a cell encodes all the information it needs to survive in the nucleotide sequence of the genome, is really exciting.”

Future directions

Although the exact mechanism underlying Rho’s specificity remains unclear, these results crack an underlying code in the composition of bacterial genomes.

Dierksheide said she hoped to perform a similar screen to characterize Rho’s specificity in Escherichia coli, which diverged from B. subtilis on the evolutionary tree an estimated 2 billion years ago and still exhibits coupled transcription-translation, where the transcribing RNA polymerase is closely followed by a translating ribosome.

The high sequence specificity of B. subtilis Rho is crucial for the protection of its runaway RNA polymerase, in which that molecular machine speeds ahead of the ribosome. A systematic comparison to E. coli Rho could help reveal how this heightened stringency arose.

This information will be critical for engineering diverse bacterial species for applications including the production of therapeutic agents. Other bacterial species, such as B. subtilis, may be better models for this process because they have abundant secretion pathways, according to Dierksheide, making it much easier to produce and isolate proteins in large quantities.

“Our findings reveal an important criterion for successful sequence design that must be considered in expression engineering,” says associate department head, associate professor of biology, and Howard Hughes Medical Institute investigator Gene-Wei Li, the lead author of the study. “There are so many cryptic messages in the genome, like the purine bias, and we are just beginning to be able to decipher what they mean.”

Two MIT faculty members named 2026 Pew Biomedical Scholars

Cell biologist Whitney Henry and immunologist Harikesh Wong will receive four years of flexible funding to advance early-career research on ferroptosis and immune decision-making.

Nina Tamburello | Nikolay Kolev | Koch Institute | Ragon Institute
June 29, 2026

Whitney Henry and Harikesh Wong have been named 2026 Pew Scholars in the Biomedical Sciences. The Pew Charitable Trusts announced the 21-member class of early-career researchers, which includes the two MIT scientists as well as two alumni, on June 16. Each scholar will receive four years of funding to pursue cutting-edge research into human health and disease. Xin Gu PhD ’22 of Dana-Farber Cancer Institute and Christina Tringides ’15 of Rice University were also selected as scholars.

Henry, the Robert A. Swanson (1969) Career Development Professor of Life Sciences and a faculty member at the Koch Institute for Integrative Cancer Research, will use the Pew scholarship to examine how a stress-induced cell death program called ferroptosis contributes to injury and regeneration in the liver. Wong, assistant professor of biology at MIT and core member at the Ragon Institute of Mass General Brigham, MIT, and Harvard, will use his award to investigate how groups of immune cells reach a “communal decision” about whether to tolerate or attack a particular target.

Whitney Henry

Henry’s research centers on ferroptosis — an iron-dependent form of regulated cell death — and its role in shaping cell fate and tissue remodeling. Her lab investigates why some cells can withstand stress while others cross the threshold for ferroptosis, focusing on the molecular, metabolic, and tissue-level cues that shape ferroptosis vulnerability. The work draws on chemical biology, metabolomics, functional genomics, and in vivo models. By defining the mechanisms that govern ferroptosis susceptibility, Henry’s group aims not only to identify novel therapies that target the most dangerous subpopulations of cancer cells, those that are highly metastatic and resistant to conventional treatment, but also to advance understanding of diseases in which ferroptosis drives tissue injury, fibrosis, or impaired repair.

Harikesh Wong

Wong investigates how groups of cells organize into networks that collectively process information and control immune responses within tissues. These networks must continually balance the body’s need to protect itself against pathogens and tumors with the need to preserve healthy tissue function. Combining the tools of immunology with high-resolution fluorescence microscopy, computational modeling, and gene manipulation, his lab seeks to map, model, and manipulate the cell-cell interactions that govern these decisions within intact tissues, revealing how subtle changes in multicellular organization and communication can shift immune responses toward pathogen clearance and tolerance, or toward autoimmunity, chronic inflammation, and cancer.

Pew scholars are chosen from applicants nominated by leading academic institutions across the United States. This year’s class of 21 was selected from 211 nominees. The incoming scholars join a legacy of more than 1,000 scientists supported by the program since 1985. During their time as scholars, they will meet annually with fellow Pew-funded scientists to build connections across a wide variety of disciplines.

“Scientific discovery is moving at a rapid pace, and now more than ever we need curious and creative researchers leading the charge,” says Lee Niswander, a 1995 Pew scholar and chair of the program’s national advisory committee. “These new biomedical scholars are prepared to meet that challenge, and I look forward to watching their research unfold.”

Raised in the “Kitchen”

Karen O’Leary, lab associate and acting supervisor in the Glassware Sterilization Facility, has become a cornerstone of the department’s operations.

Samantha Edelen | Department of Biology
June 25, 2026

Early mornings in the halls of Building 68 feature the sounds of rolling wheels on big metal carts, the rattling of glassware, the whooshing of faucets, and the clanking of autoclaves.

These aren’t the sounds of researchers at work, but rather those of keeping the labs sterilized and stocked with the sundries of research: pipette tips, test tubes, flasks, petri dishes, and more.

Orchestrating this sunrise cacophony and the staff that undertakes it is Karen O’Leary, lab associate and acting supervisor in the Glassware Sterilization Facility, also known as the “kitchen.”

Thanks, in part, to O’Leary’s proactivity and hard work, the kitchen staff were recently recognized with an MIT Excellence Award in 2025 for exceptional contributions in service of the community.

“My goal is to get the scientists everything they need to do their research,” O’Leary says. “I’m good at what I do.”

O’Leary admits she did not always possess such confidence. In almost 40 years at MIT, O’Leary has grown into this critical role for the department, and the department itself has evolved, moving into a brand-new building and away from previously standard practices like submerging equipment in acid for sterilization.

From rookie to running the show

On Sept. 7, 1987, Karen O’Leary joined the MIT community as a staff member for the first time. The 18-year-old was fresh from vocational high school, where she studied cosmetology but felt too shy to pursue that as a career. She was also nervous about joining a research institution.

“When I started, I didn’t even know what a beaker was,” she recalls.

Too embarrassed to admit in her interview that she couldn’t remember her brand-new home phone number, “I just made one up.” Fortunately, this didn’t prevent her from getting the job, where she worked under the mentorship of Thelma Watkins, who would retire in 1996 after 21 years at MIT. Watkins was critical for instilling a good work ethic and boosting O’Leary’s confidence.

“She taught me to show up every day, and work hard, and laugh,” O’Leary says.

Even now, O’Leary continues to bring joy to that daily diligence, for herself and for her staff.

“Karen is always on top of things,” says longtime friend and fellow Lab Associate AnnMarie Budhai. “She doesn’t refuse work and always goes above and beyond.”

Facilities and Operations Manager Cesar Duarte says that O’Leary’s long tenure, support, and knowledge have been invaluable as he transitioned into his role in Building 68 starting in 2023.

“Karen is one of those people who makes everything around her run more smoothly and more pleasantly,” Duarte says.

Better, faster, safer

Although some might consider it drudgery, O’Leary says that washing glassware is her favorite task.

“I like that when I wash, I can see the job is complete at the end of the day,” she says.

Although washing glassware is a perennial task, safety and efficiency have come a long way in the past 38 years. More-effective autoclaves and dishwashers have eliminated steps like steaming to dissolve agar solvents before autoclaving, and scrubbing individual test tubes before washing.

O’Leary was working for the department in 2011 when Building 68 piloted a new approach to MIT’s management of regulated medical waste (RMW), such as petri dishes, blood, and needles — the new system, which is cheaper and produces less waste, is now used by all departments at MIT that produce RMW.

“EHS [the Environment, Health and Safety Office] has come really far — I’m glad we got away from acid,” O’Leary notes of the bygone era of submerging glass pipettes for sterilization. “Back then, no one knew of a better way.”

Other tasks include cleaning velvets, which are used for replicating bacterial colonies on petri dishes, and pouring agar plates.

“Everyone knows how to do almost every job, so we can take turns doing different tasks,” O’Leary says. “If you get sick, there’s always someone to cover.”

All in the family

For O’Leary, kinship with MIT has spanned generations. O’Leary was raised in Weymouth, Massachusetts, by a father who worked at MIT as a supervisor in the sheet metal shop. Having raised children of her own, now grown, O’Leary came to greatly appreciate the flexibility her job has granted her.

“I’ve had great work-family balance here,” she says. Even though she’s often at work more than an hour before the researchers that the kitchen serves, “The hours are great, and with MIT Health right across the street, it was easy to take everyone to doctors’ appointments.”

She’s also gained a chosen family at MIT, spending breaks at work taking long walks along the Charles River, “talking about anything and everything” with colleagues like Budhai and Lab Aide Janet Katin.

“We really grew up together,” she says.

Working at MIT has provided O’Leary with support and community, and she’d like to pay it forward. In addition to strolling with colleagues, she hits the gym to help maintain the energy required for her highly active work.

“I don’t like sitting around,” she says.

In addition to maintaining her stamina at work, she hopes that taking care of herself will keep her actively involved if she ever has grandchildren, and enable her to help neighborhood kids when she someday retires.

“I owe a lot to MIT,” she says. “I have been allowed to work hard and get satisfaction and have been appreciated and given space to care for my family.”

O’Leary returns this care to the Department of Biology in spades.

“It’s an understatement to say that Biology is lucky to have her,” says Duarte. “Karen’s overflowing energy, attention to detail, and care for the Biology research community are nothing short of amazing.”

Advancing stem cell research and building the next generation of biologists

Biology PhD student Giselle Valdes (Reddien Lab) studies stem cell regeneration while encouraging aspiring students and researchers.

Stefanie Koperniak | Division of Graduate and Undergraduate Education
June 11, 2026

As an undergraduate at Florida International University, Giselle Valdes tackled rigorous studies in the school’s Honors College while simultaneously caring for family members with medical needs.

“I think that the choice to pursue any field in the space of biology and medical research was entirely shaped by having to be there for my family,” says Valdes.

As a McNair Scholar and biomedical engineering major who also did extensive research in biochemistry, she leaned more toward undergraduate courses in mechanical and electrical engineering that were geared primarily toward equipping students to build medical devices. She began to shift her research interests more firmly into biology, however, the summer before her senior year in 2018. She spent 10 weeks on the MIT campus as a participant in the Bernard S. and Sophie G. Gould MIT Summer Research Program in Biology (BSG-MSRP-Bio), working in the lab of Associate Professor Eliezer Calo PhD ’11, also a former BSG-MSRP-Bio participant. The Calo Lab focuses on ribosomes, small cellular particles that translate RNA into proteins, and looks at how mutations in ribosome development can lead to disorders.

After working in Calo’s lab, she could see herself as a biology graduate student at MIT. In January 2019, she attended the MIT biology department’s Quantitative Methods Workshop, a weeklong, intensive workshop designed to introduce non-MIT undergraduates to tools and programming languages used to analyze experimental data in biology and neuroscience. While there, she was elated to receive an email from the department inviting her to interview for the PhD program. She was accepted and began her doctoral studies in the fall of that year.

“When I think about my experiences at MIT, both as an undergraduate in MIT programs and as a PhD candidate in biology, I think about all the great mentors who have helped me along the way,” says Valdes. “I’ve also really valued the richly collaborative community, and being able to take a lot of risks in how I address the questions I have the opportunity to pursue.”

Researching stem cell regeneration

Since she came from a biomedical engineering background, Valdes spent the first year of the biology doctoral program taking foundational biology courses and working in different labs to decide which type of research she wanted to do. She gravitated toward cell and developmental biology and joined the lab of Professor Peter Reddien, associate director of the Whitehead Institute for Biomedical Research. Valdes was awarded an MIT Fund for the Future of Science Fellowship to support her research.

“Giselle is doing terrific work on a fundamental problem related to adult stem cells and regeneration — how do progenitor cells choose what cell types to make? Fate choice in progenitors is typically studied in embryogenesis, and how it occurs in the context of adult regeneration is poorly understood and very important to address,” says Reddien.

Valdes has worked extensively with stem cells in highly regenerative flatworms, called planaria. analyzing the process of “cell fate choice,” or how cells determine which specific cell types and functions to develop. To date, Valdes, Reddien, and other researchers have studied “neighborhoods” of neoblasts (adult stem cells) and their fate choices, finding that different neighboring stem cells often chose different fate options — suggesting that cell fate choices are largely made by processes autonomous to individual cells.

Her current research aims to better understand the driving mechanism for cell fate choice, both within planaria and an additional model system: the evolutionarily distant acoel Hofstenia miamia.

“A lot of the things I’m doing in my current project have involved developing techniques that didn’t previously exist in our model organism,” says Valdes.

Working on model systems with limitations in the toolkit traditionally available to more well-established systems, such as transgenics, has allowed her to be creative in the techniques she applies to determine how stem cells choose what to become. It has also opened doors to collaborations, such as one with Ye Zhang of the Manalis Lab in the biological engineering department (now an assistant professor of biomedical engineering at Virginia Tech), that have allowed Valdes and team to sort neoblasts in novel ways based on their morphology, and better relate that to their dynamic state.

In summer 2024, Valdes mentored a BSG-MSRP-Bio student who now works with her on a current research project.

“She’s been with me as a technical assistant in the lab now for over a year, and we’ve been able to work on one of my projects together,” says Valdes. “It’s been exciting to come full circle in this way.”

Teaching and mentoring, near and far

In addition to her research, Valdes devotes a lot of her time to teaching and mentoring, both for MIT biology students and younger students discovering an interest in STEM.

“It’s been so rewarding to have a lot of opportunities to do for others what has been done for me,” she says.

Valdes has worked with secondary students both locally and abroad. She participates in the biology department’s developmental biology lab for high-school students and teaches in an annual biology lecture series for high schoolers. She has worked with the Enroot program from Cambridge Community Services, acting as a direct mentor to local high-school and community college students. At the Whitehead Institute’s Expedition: Bio program, for middle- and high-school students, she runs a planarian workshop. And she gives lab tours through the Whitehead Discovery Lab initiative, engaging in discussion with local high-school students.

Valdes has also assisted with a hackathon for Sprouting, a social impact venture providing STEM education opportunities to under-resourced communities in Puerto Rico. Sprouting was launched by Taylor Baum, a doctoral student in MIT’s Department of Electrical Engineering and Computer Science. Valdes taught coding essentials to Spanish-speaking middle- and high-school students in Puerto Rico.

“That was really emotional,” says Valdes. “The parents were so grateful, and there were kids who were clearly brilliant and gifted. They were able to really take off with the tools that we gave them.”

In her department, Valdes has been a teaching assistant for classes 7.003 (Applied Molecular Biology Laboratory) and 7.03 (Genetics). She is also a teaching assistant for the Quantitative Methods Workshop and teaches a Python module to students in the program.

“Giselle may be quite small in physical stature, yet she dominates the room when she speaks, and commands the full attention of an audience of 80 students when giving a lecture,” says Mandana Sassanfar, a biology senior lecturer and director of outreach who runs the Quantitative Methods Workshop. “She is highly respected both for her knowledge and the way she interacts with people. She is extremely approachable, very generous with her time, and always very supportive and encouraging. She is a wonderful mentor, teacher, and scientist.”

Valdes says she is always happy to help mentor undergrads and graduate students. She is co-founder and coordinator of the MIT Biology Application Assistance Program (BAAP), which aims to demystify the graduate school application process and offer interested applicants the tools and direct mentorship necessary for putting together a successful application. She also helped to coordinate, and has been an active participant in, the MIT BioPals Program, a student-organized peer mentorship initiative within the department that connects incoming first-year graduate students with senior graduate students. During the Covid-19 pandemic, this program provided critical support and social connection for new students navigating remote learning and social distancing.

After she completes her doctoral program, she envisions pursuing a postdoc and, ultimately, a faculty role, citing her passion for both academic research and teaching.

“My goal is to stay in academia in some way,” says Valdes. “I love mentorship and curiosity-driven science.”

Enzymes that assemble into droplets can speed up cellular reactions

MIT biologists find highly concentrated droplets can help cells keep enzymes organized and control growth signals.

Anne Trafton | MIT News
June 1, 2026

Within the past decade, biologists have discovered that one strategy cells use to keep their contents organized is a phenomenon known as phase separation.

Similar to the way oil forms droplets that float in a vinegar solution, proteins inside cells can phase separate to form highly concentrated droplets that keep them organized within the cell. In a new study, MIT researchers have now shown that this droplet formation is critical for controlling the function of a class of enzymes called kinases.

The researchers found that condensing into droplets optimizes the biochemical conditions needed for kinases to catalyze reactions, allowing them to more rapidly activate cell signaling pathways. In some cases, droplet formation can even change which reactions the kinases perform.

“Many biological molecules have this propensity to spontaneously separate. We were really interested in asking, if we have these kinases forming droplets, what is the consequence of that in the context of signaling?” says Lindsay Case, an assistant professor of biology at MIT and the senior author of the study.

Learning more about how these droplets form could help researchers design drugs that target kinases, some of which can be overactive in cancer cells.

“Understanding the chemistry of these compartments, and what molecules go into them and what molecules don’t go into them, could help us design drugs that better localize to their target of interest,” Case says.

Nicholas Lea, an MIT graduate student, is the lead author of the paper, which appears today in Cell Reports.

Forming droplets

Since her days as a graduate student, Case has been studying how the physical organization of molecules inside cells affects their function. As a postdoc, she began studying how phase separation might affect a signaling pathway that allows cells to sense when they’re attached to their environment, so they can respond appropriately.

Some of the proteins in this pathway are kinases, which activate other proteins by adding phosphate groups to them. Kinases can also activate themselves through a process called autophosphorylation.

“Inside of the cell, you have these kinase molecules that are responsible for carrying a signal through the cell, and we know that the organization of these molecules changes. When the information is present, they’re organized in a different way than when the information is not present,” Case says. “We think that having the right molecules in the right place is incredibly important for the right biochemistry to occur.”

Phase separation is one of the methods that cells appear to use for this organization. The most familiar example of phase separation can be seen in a salad dressing, where oil forms droplets to minimize contact with water-based vinegar. Proteins can phase separate when they are highly concentrated, leading them to self-assemble into dense droplets floating in the cell’s cytoplasm.

Case hypothesized that this phase separation, which brings kinases together at a high density, might help cells to boost the enzymes’ activity because they are more likely to bump into and phosphorylate each other.

In this study, Case and Lea set out to test that hypothesis, focusing on an enzyme called focal adhesion kinase (FAK). This kinase, which becomes activated when cells attach to their surrounding environment, activates pro-growth and pro-survival signals. In cancer cells, this signaling pathway can go awry, allowing cells to proliferate even when they detach from their original locations.

Scientists already knew that when cells are properly attached to their environment, that adhesion signal causes FAK to accumulate at the cell membrane. In the new study, the MIT team mimicked that effect by overexpressing FAK in cells. These cells were floating freely in a solution, not attached to any surface. Even so, the high concentration of FAK caused the kinase to phase separate into droplets, which turned on the pro-growth signal.

“It was surprising that just by condensing this protein into a droplet, you can actually turn on a signaling pathway that should be turned off,” Case says. “If FAK concentration is too high, you’re always getting these droplets and you’re always signaling, regardless of what the receptors that are supposed to be controlling this are doing.”

The findings suggest that in cancer cells, overexpression of FAK may lead to phase separation, which then helps to drive cancer progression and metastasis.

“It may be that for some kinases, you’re not supposed to form these droplets in the cytoplasm because it leads to this always-on signal, and then the cells no longer listen to the information coming from the environment,” Case says.

Interfering with FAK’s ability to form droplets could offer a new strategy for cancer drug development, she says.

Controlling reactions

The researchers also studied two other kinases, Mst2 and Abl. They found that these enzymes could also phase separate at high concentrations, and that this increased their activity. While phase separation of FAK in the cytoplasm may occur only in cancerous cells, for Mst2, it appears to be a strategy that healthy cells use to control a signaling pathway called Hippo, which promotes cell growth and survival.

Additionally, for both Mst2 and Abl, the researchers discovered that phase separation can lead the enzymes to phosphorylate additional targets, which may lead them to activate different signaling pathways.

“It’s not just that you’re getting faster phosphorylation, but in those cases, the patterns of what is actually getting phosphorylated were very different inside of the droplet compared to what might be happening in a non-droplet context,” Case says. “The kinase is able to phosphorylate amino acid residues beyond the set of canonical sites that have been described before.”

The researchers also found that when these droplets form, they attract high concentrations of ATP, the molecule that kinases use as a source of phosphate. This occurs because kinases tend to contain floppy sections containing many positively charged amino acids, which attract negatively charged ATP.

Using a machine-learning model, the researchers predicted that about 45 percent of the 500 kinases found in human cells would have the ability to form droplets like those seen in this study. Those kinases were also more likely to be highly positively charged, which could help them to recruit ATP into the droplets.

In future work, Case hopes to explore the possibility of designing drugs that could mimic ATP’s ability to be attracted into droplets within a cell, which could help reduce negative side effects of the drugs.

“By localizing drugs to the compartment where your target localizes, that could reduce off-target effects by concentrating the drug with the target of interest and reducing interactions with other molecules,” Case says.

The research was funded by a Searle Scholars Program Award, the U.S. Air Force Office of Scientific Research, the National Institutes of Health, the Royal G. and Mae H. Westaway Family Memorial Fund, and a David H. Koch Graduate Fellowship.

Scientists map which genes are active in a developing seed to build hardier crops

Many of the basic biological processes that allow seeds of global food staples like wheat, rice, and corn, to grow, transport nutrients, and develop useful traits like withstanding heat and drought are not yet fully understood. A new gene expression map of seed development offers a framework to better understand, and even guide, seed development to improve crop productivity.

Shafaq Zia | Whitehead Institute
May 19, 2026

Seeds like wheat, rice, and corn are at the center of the global food supply and provide most of the daily calories consumed worldwide. But despite their importance, scientists still do not fully understand many of the basic biological processes that allow these seeds to grow, transport nutrients, and develop traits that determine crop resiliency.

With fluctuating environmental conditions and other stressors threatening agriculture, there is a need to develop hardier crops better able to withstand heat, drought, and changing soil conditions. Scientists are increasingly looking to understand the hidden biology of seed development that could one day help them achieve this.

Now, researchers in the lab of Mary Gehring have created a detailed gene expression “map” of seed development in Arabidopsis thaliana, a small flowering plant in the mustard family that is widely used to study plant biology and is closely related to major crops like canola.

This map, also known as a transcriptional atlas, shows which genes are turned on or off in different cell types as the seed develops. Active genes make messenger RNA (mRNA) that guides the production of proteins necessary for cellular processes. By tracking which genes are active where, researchers can better understand the role each cell type plays across different stages of seed development.

The work, published May 21 in Nature Plants, offers scientists new clues about how plants coordinate key biological processes tied to agriculturally significant traits, including seed size and nutrient storage.

“Seeds are fundamental to sustaining human life,” says Caroline (Carly) Martin, lead author of the paper and a graduate student in the Gehring Lab. “By building this atlas, we now have a framework researchers can use to start asking much more precise questions about how seeds develop and if those processes might eventually be improved in different crops.”

Unlike previous atlases of Arabidopsis, which do not distinguish many cell types due to technological limitations, the new atlas provides a more complete and higher resolution view of the developing seed. The researchers have captured seed development at three precisely timed stages after pollination when the plant embryo, the nutrient-rich tissue that feeds it (called the endosperm), and the surrounding tissues from the mother plant rapidly grow and reorganize. Using this dataset, they have identified where genes that regulate how seeds grow and store nutrients are active.

The researchers have found a small group of cells near the plant embryo that activate genes involved in producing brassinosteroids, plant hormones that regulate growth. Previous studies had shown that disrupting the production of this hormone can reduce seed size, but it was not known where within the developing seed the hormone is made.

The new data shows that these hormone-producing cells sit directly next to cells in the endosperm that might respond to the hormone. This close arrangement suggests the two cell types may work together to help fine-tune seed size.

The atlas has also revealed that the endosperm, which nourishes the embryo during development and later becomes the edible portion of many staple crops, contains far more specialized cell types than previously understood by researchers.

The team has identified a small “founder” population of cells that may help establish a key region of the endosperm located at the boundary where nutrients enter the seed from the mother plant.

Because the amount and timing of resources supplied by the mother plant determine how much energy the seed can store, this region of the endosperm helps shape the seed’s nutritional profile. These reserves — oils, starches, and proteins — are essential for both seed development and human nutrition.

These findings, taken together, could allow researchers to better understand — and even guide — seed development to improve crop productivity.

“We’re already seeing that seed filling in many crops is vulnerable to heat stress,” says Gehring, who is also a professor of biology at MIT and an investigator at the Howard Hughes Medical Institute (HHMI). “If we are to solve the humanitarian crises of food insecurity and malnutrition, we need to understand, at a fundamental level, how seeds of different crops form, store nutrients, and survive environmental stress.”

Caroline A. Martin, Kylee R. Cogdill, Alesandra L. Pusey, and Mary Gehring. “A transcriptional atlas of early Arabidopsis seed development suggests mechanisms for inter-tissue coordination.” Nature Plants, May 21, 2026. https://doi.org/10.1038/s41477-026-02295-8

How tissues tune immune responses to match the threat

Organs which interface with the outside world, like the lungs, skin, and intestines, must balance responding quickly to threats while also avoiding triggering unnecessary inflammation. A new study has found that immune sensitivity in the communities of epithelial cells that line the lungs is not evenly distributed, with cells deeper in the tissue more likely to sound the alarm in response to a threat such as viruses, microbes, allergens, and other particles.

Mackenzie White | Whitehead Institute
May 14, 2026

Barrier organs that form boundaries between the body and the outside environment, such as the lungs, skin, and intestines, face a difficult balancing act. They must respond quickly to threats such as infection, but they also need to avoid triggering unnecessary inflammation that can damage the tissue. A new study led by Whitehead Institute member Pulin Li and graduate student in her lab Diep Nguyen reveals one way the lung manages that tradeoff.

Published on May 15 in Cell Systems, the research found that immune sensitivity is not evenly distributed across the lung. Instead, it arranges in tiers: cells at the outer surface respond cautiously, while cells deeper in the tissue are more likely to sound the alarm when a threat breaks through.

“The central question was how tissues balance the benefits and harmful effects of immune activation when they face different degrees of danger or stress,” says Li, who is also a professor of biology at MIT. “Too little immune activation leaves the tissue unprotected, but too much can create inflammation and damage.”

The team focused on the lung, where epithelial cells line the airways and air sacs and form a physical barrier between the body and the outside world. These cells sit at the point of first contact with inhaled viruses, microbes, allergens, and other particles. For that reason, they are often thought of as front-line defenders.

But the new study suggests that the lung’s outermost defenders are deliberately cautious.

Using mouse models of influenza infection and imaging methods that allowed them to measure infection and immune responses in individual cells, the researchers found that epithelial cells were the least likely to respond to infection by producing interferons, signaling proteins that help alert the immune system. Cells deeper in the tissue, especially endothelial cells that line blood vessels, were much more likely to respond.

This arrangement suggests that the lung uses location as a clue to the seriousness of a threat. A stimulus that remains at the surface may not require a large immune response. But when infection breaches the epithelial barrier and reaches deeper tissue, the lung treats that as a more dangerous threat and activates a stronger defense.

“A less severe threat only requires a lower level of immune response,” says Nguyen. “As a threat goes deeper into the tissue, the inner cell types can encode that information and indicate that the threat has invaded further.”

The researchers traced these differences in sensitivity, in part, to immune-sensing proteins called pattern recognition receptors. These receptors detect molecular signs of infection or damage. One receptor, RIG-I, helps cells recognize viral RNA. Epithelial cells had relatively low levels of RIG-I and related sensors, while deeper stromal cells had higher levels.

That lower sensitivity appears to protect the lung from unnecessary damage. When the researchers increased RIG-I levels in lung epithelial cells in mice, the animals mounted a stronger immune response to a non-infectious inflammatory trigger. But the heightened response caused more tissue damage and interfered with repair.

The finding helps explain why the lung’s surface cells may be tuned not to overreact. The lung constantly encounters harmless or low-level irritants. If epithelial cells responded too readily, they could turn minor disturbances into damaging false alarms.

The researchers also found evidence that similar patterns may exist in other barrier organs, including the intestine and trachea. That raises the possibility that spatially tiered immune sensing is a broader strategy for protecting organs that face the outside world.

“One impact of this work is that it helps us look at an old question in a new way: how do tissues balance protection with tissue damage?” says Nguyen. “We can start to understand that when we look at the building blocks of the tissue and how they work together.”

Li says the work also reflects the value of studying tissues as communities of cells rather than collections of identical responders.

“To understand physiology, you have to take a multicellular approach,” she says. “Thinking about tissues as communities of cells can reveal new insights into how they function.”

Diep H. Nguyen, Jiakun Tian, Sean-Luc Shanahan, Connie Kangni Wang, Tyler Jacks, Xiao Wang, and Pulin Li. “A tissue-scale strategy for sensing threats in barrier organs.” Cell Systems, May 14, 2026. https://doi.org/10.1016/j.cels.2026.101611

Whitney Henry among MIT affiliates named 2026 Searle Scholars

Computational neuroscientist Sven Dorkenwald and cell biologist Whitney Henry, along with two MIT alumni, are recognized for their exceptional early-career research contributions.

Julie Pryor | Bendta Schroeder | McGovern Institute for Brain Research | Koch Institute
May 20, 2026

MIT scientists Sven Dorkenwald and Whitney Henry have been named 2026 Searle Scholars, an award given annually to 15 exceptional early-career researchers in the fields of biomedical sciences and chemistry. Dorkenwald is an assistant professor of brain and cognitive sciences and an investigator at the McGovern Institute for Brain Research. Henry is the Robert A. Swanson (1969) Career Development Professor of Life Sciences and an intramural faculty member at the Koch Institute for Integrative Cancer Research.

In addition, MIT alumni Irene Kaplow ’10 and Jared Mayers PhD ’15 were also honored.

Chosen by a scientific advisory board, Searle Scholars are considered among the most creative young researchers pursuing high-risk/high-reward research. The Searle Scholars Program is funded through the Searle Funds at The Chicago Community Trust and administered by Kinship Foundation. Each scholar will each receive $450,000 in flexible funding to support their work over the next three years.

Sven Dorkenwald

Sven Dorkenwald is a computational neuroscientist investigating the organizational principles of neuronal circuits. The synaptic connectivity of neurons, their connectome, is fundamental to how networks of neurons function. Dorkenwald develops computational and collaborative tools to map, analyze, and interpret synapse-resolution connectomes. His work has led to large connectomic reconstructions of the fruit fly brain and parts of mammalian brains. He uses these connectomes to investigate the architecture of neuronal circuits and how their structure supports complex computations.

“As I establish my new lab, the Searle Scholars Award will help us launch ambitious projects and set our long-term scientific direction,” says Dorkenwald. “I am deeply grateful for the support from the Kinship Foundation and look forward to interacting with this amazing cohort of Searle Scholars.”

Dorkenwald joined the faculty of MIT in 2026 as an assistant professor in the Department of Brain and Cognitive Sciences and an investigator at the McGovern Institute. He earned a BS in physics and an MS in computer engineering from the University of Heidelberg, followed by a PhD in computer science and neuroscience at Princeton University in 2023 under the mentorship of Sebastian Seung and Mala Murthy. Dorkenwald completed his postdoctoral training as a Shanahan Research Fellow at the Allen Institute and the University of Washington, while serving as a visiting faculty researcher at Google Research.

Whitney Henry

Whitney Henry investigates the potential of ferroptosis, an iron-dependent form of cell death, for developing novel therapies that target subpopulations of cancer cells that are highly metastatic, therapy-resistant, and therefore critical instigators of tumor relapse. Her research is focused on uncovering the molecular factors influencing ferroptosis susceptibility, investigating its effects on the tumor microenvironment, and developing innovative methods to manipulate ferroptosis resistance in living organisms, drawing from functional genomics, metabolomics, bioengineering, and a range of in vitro and in vivo models.

“I am incredibly grateful to the Kinship Foundation for supporting our research and giving us the freedom to ask bold, curiosity-driven scientific questions,” says Henry. “This support allows us to pursue ambitious ideas, take creative risks, and embark on new research directions.”

Henry joined the MIT faculty in 2024 as an assistant professor in the Department of Biology and a member of the Koch Institute, and is currently an HHMI Freeman Hrabowski Scholar. She received her bachelor’s degree in biology with a minor in chemistry from Grambling State University and her PhD from Harvard University. Following her doctoral studies, she worked in the lab of Robert Weinberg at the Whitehead Institute for Biomedical Research and was supported by fellowships from the Jane Coffin Childs Memorial Fund for Medical Research and the Ludwig Center at MIT.

Alumni also honored

Irene Kaplow ’10, a graduate of the MIT Department of Mathematics, is an assistant professor in the Department of Biology and the Ray and Stephanie Lane Computational Biology Department at Carnegie Mellon University. Her selection as a Searle Scholar is for “deciphering transcriptional regulatory mechanisms underlying mammalian dietary phenotype evolution and their relationships to transcriptional regulatory responses to changes in diet.”

Jared Mayers PhD ’15, who earned his doctorate from the MIT Department of Biology, is an assistant professor at the Fred Hutchinson Cancer Center at the University of Washington. His selection as a Searle Scholar is for “a reverse-translational framework to decipher metabolic vulnerabilities of bacterial pathogens.”

Biologist Joey Davis explores how cells build complex structures

His studies have shed light on the assembly instructions that govern ribosomes, the critical protein-building machines of the cell.

Anne Trafton | MIT News
May 5, 2026

Ribosomes, the cellular machines that assemble proteins, are made from dozens of proteins and RNA molecules. Putting all of those pieces together is a complex puzzle — one that MIT Associate Professor Joey Davis PhD ’10 revels in trying to solve.

Understanding how these structures form and later break down could help researchers learn more about how disruptions of these fundamental processes can lead to disease. But, as Davis points out, it’s also an interesting biological question.

“Our long-term goal is to really understand how the natural world assembles these huge complexes rapidly and efficiently. It’s a fundamentally interesting question to think about how these things get put together,” he says.

His work has helped reveal that unlike building a house, which happens in a prescribed sequence of steps — pouring the foundation, building the frame, putting on the roof, then doing electrical and plumbing work — ribosomes can be assembled in a more flexible way. Cells can even skip an assembly step and then come back to it later.

“In these natural systems, it seems like the assembly pathways are much more dynamic and flexible,” he says. “It appears that evolution has selected pathways that aren’t strictly ordered in the way we would think about an assembly line, where you always put in one component, then the next, and then the next. We’re excited to understand the selective advantages of such approaches.”

A love of discovery

Davis’ interest in how things are put together developed early in life, inspired by his father, a carpenter who framed houses. During the mid-1980s, the family moved from Colorado to Southern California, where his father worked in construction during a housing boom there.

“I was always interested in building things, which I think probably came from being around my dad and other builders,” Davis says.

As an undergraduate at the University of California at Berkeley, where he majored in computer science and biological engineering, Davis’ interests turned toward smaller scales, in the realm of cells and molecules. During his junior year, he started working in the lab of chemistry professor Michael Marletta, who studies molecular-level biological interactions.

In the lab, Davis investigated how enzymes that contain heme are able to preferentially bind to either oxygen or nitric oxide, two gases that are very similar in structure. That work kindled a love of studying the natural world and pursuing discoveries in fundamental science.

“Being in the Marletta lab and seeing students and postdocs that were really passionate about these problems had a big impact on me,” Davis says. “The goal was to understand the fundamentals of how molecular discrimination works, and the idea of discovery for the sake of discovery was thrilling.”

After graduating from Berkeley, Davis spent another year working in Marletta’s lab, and then a year working odd jobs, before heading to MIT to pursue a PhD in biology. There, he worked with Professor Bob Sauer, now emeritus, who studied the relationship between protein structure and function, with a particular focus on the molecular machines that degrade or remodel proteins.

Davis’ thesis research centered on enzymes called AAA proteases, which remove damaged proteins from cellular membranes and send them to cell organelles that break them down. In addition to studying the structure and function of the proteases, Davis worked on ways to engineer them to tag specific proteins for destruction.

That work led him into synthetic biology, which he used to develop genetic parts that drive production of proteins of interest. Some of those parts ended up being used by the biotech startup Ginkgo Bioworks, where Davis took a job as a senior scientist after graduating.

Working at Ginkgo Bioworks allowed Davis to stay in Boston while his partner finished her PhD. The couple then moved back to California, where Davis worked as a postdoc at Scripps Research, which was home to one of the first direct electron detection cameras for cryo-electron microscopy (cryo-EM). These detectors allow researchers to generate structures with near atomic resolution. At Scripps, Davis began using them to study ribosomes as they were being assembled.

Peering into the ribosome

After joining the MIT faculty in 2017, Davis continued his work on ribosomes and assembled a lab group that includes students from a variety of backgrounds who work together to develop new ways to explore biological phenomena.

“I have a mix of method developers and biologists in the group, and the work from each of them informs each other,” Davis says. “My lab goes back and forth between building sets of tools to answer biological questions, and then as we’re answering those questions, it motivates the next generation of tool development.”

During ribosome assembly, RNA molecules fold themselves into the correct shapes, creating docking sites for proteins to attach. Then, more RNA molecules come in and fold themselves into the structure.

“It’s a beautifully coupled process by which the cell folds hundreds of RNA helices and binds on the order of 50 proteins, and it does it in two minutes from start to finish. E. coli does this 100,000 times per hour, and it’s amazing how rapid and efficient the process is,” Davis says.

Cryo-EM allows scientists to capture this process in minute detail. It can be used to take hundreds of thousands of two-dimensional images of ribosome samples frozen in a thin layer of ice, from different angles. Computer algorithms then piece together these images into a three-dimensional representation of the ribosome.

To gain insight into how ribosomes are assembled, researchers can stall the process at different points and then analyze the resulting structures. In 2021, Davis’s lab developed a new method called CryoDRGN, which uses neural networks to analyze cryo-EM data and generate the full ensemble of structures that were present in the sample.

This work has shown that when certain steps of ribosome assembly are blocked, many different structures result, suggesting that the assembly can occur in a variety of ways.

In future work, Davis aims to dramatically increase the throughput of cryo-EM to generate datasets of protein structures that could help improve the AI-based models that are now used to predict protein structures.

“There are still huge swaths of sequence space that these models are very poor at predicting, but if we could collect data on those sequences en masse, that could potentially serve as key training data for a next-generation protein structure prediction method that could fill out that space,” he says.