Whitehead Institute researchers are using a modified CRISPR/Cas9-guided activation strategy to investigate the most frequent cause of intellectual disability in males.
Nicole Giese Rura | Whitehead Institute
February 15, 2018
Fragile X syndrome is the most frequent cause of intellectual disability in males, affecting one out of every 3,600 boys born. The syndrome can also cause autistic traits, such as social and communication deficits, as well as attention problems and hyperactivity. Currently, there is no cure for this disorder.
Fragile X syndrome is caused by mutations in the FMR1 gene on the X chromosome, which prevent the gene’s expression. This absence of the FMR1-encoded protein during brain development has been shown to cause the overexcitability in neurons associated with the syndrome. Now, for the first time, researchers at Whitehead Institute have restored activity to the fragile X syndrome gene in affected neurons using a modified CRISPR/Cas9 system they developed that removes the methylation — the molecular tags that keep the mutant gene shut off — suggesting that this method may prove to be a useful paradigm for targeting diseases caused by abnormal methylation.
Research by the lab of Whitehead Institute for Biomedical Research Founding Member Rudolf Jaenisch, which is described online this week in the journal Cell, is the first direct evidence that removing the methylation from a specific segment within the FMR1locus can reactivate the gene and rescue fragile X syndrome neurons.
The FMR1 gene sequence includes a series of three nucleotide (CGG) repeats, and the length of these repeats determines whether or not a person will develop fragile X syndrome: A normal version of the gene contains anywhere from 5 to 55 CGG repeats, versions with 56 to 200 repeats are considered to be at a higher risk of generating some of the syndrome’s symptoms, and those versions with more than 200 repeats will produce fragile X syndrome.
Until now, the mechanism linking the excessive repeats in FMR1 to fragile X syndrome was not well-understood. But Shawn Liu, a postdoc in Jaenisch’s lab and first author of the Cell study, and others thought that the methylation blanketing those nucleotide repeats might play an important role in shutting down the gene’s expression.
In order to test this hypothesis, Liu removed the methylation tags from the FMR1 repeats using a CRISPR/Cas9-based technique he recently developed with Hao Wu, a postdoc in the Jaenisch lab. This technique can either add or delete methylation tags from specific stretches of DNA. Removal of the tags revived the FMR1 gene’s expression to the level of the normal gene.
“These results are quite surprising — this work produced almost a full restoration of wild type expression levels of the FMR1 gene,” says Jaenisch, whose primary affiliation is with Whitehead Institute, where his laboratory is located and his research is conducted. He is also a professor of biology at MIT. “Often when scientists test therapeutic interventions, they only achieve partial restoration, so these results are substantial,” he says.
The reactivated FMR1 gene rescues neurons derived from fragile X syndrome induced pluripotent stem (iPS) cells, reversing the abnormal electrical activity associated with the syndrome. When rescued neurons were engrafted into the brains of mice, the FMR1 gene remained active in the neurons for at least three months, suggesting that the corrected methylation may be sustainable in the animal.
“We showed that this disorder is reversible at the neuron level,” says Liu. “When we removed methylation of CGG repeats in the neurons derived from fragile X syndrome iPS cells, we achieved full activation of FMR1.”
The CRISPR/Cas-9-based technique may also prove useful for other diseases caused by abnormal methylation including facioscapulohumeral muscular dystrophy and imprinting diseases.
“This work validates the approach of targeting the methylation on genes, and it will be a paradigm for scientists to follow this approach for other diseases,” says Jaenisch.
This work was supported by the National Institutes of Health, the Damon Runyon Cancer Foundation, the Rett Syndrome Research Trust, the Brain and Behavior Research Foundation, and the Helen Hay Whitney Foundation. Jaenisch is co-founder of Fate Therapeutics, Fulcrum Therapeutics, and Omega Therapeutics.
New cancer research initiative eyes individualized treatment for patients.
Koch Institute
February 1, 2018
Details matter — perhaps most noticeably in the fight against cancer. Some patients respond to a given anticancer therapy, and some do not. A new initiative at MIT takes aim at those details, and the name of the game is precision.
The recently launched MIT Center for Precision Cancer Medicine (CPCM) is housed within MIT’s Koch Institute for Integrative Cancer Research and headed by physician-scientist Michael B. Yaffe, the David H. Koch Professor of Science and professor of biology and biological engineering. The center brings together leading Institute faculty members to focus on key research themes to accelerate the clinical translation of novel cancer discoveries, treatments, and technologies.
Engineering approaches to the clinic
While other institutions have begun efforts in precision medicine as well, the MIT Center for Precision Cancer Medicine stands out for using engineering approaches to solve complex clinical challenges in cancer treatment that are rooted in biology. In particular, the CPCM combines understandings of biological circuitry — along with engineering, computational, and mathematical techniques (as well as genomic ones) — to focus on signaling networks and pathways that are aberrantly regulated in cancer cells. This strategy is supported by the fact that most state-of-the-art molecularly targeted cancer therapies are focused on these key pathways.
At its core, the CPCM is driven by both internal and external collaboration, and is devoted to translational research to help the substantial number of patients who do not respond well to traditional cancer therapies — for example, those with triple-negative breast cancer, ovarian cancer, non-small cell lung cancer, or advanced prostate cancer.
To improve outcomes for these patients, CPCM investigators are focused on four key areas of research. First among these is identifying and targeting the processes, signals, and mechanisms that determine an individual patient’s response to chemotherapy. Recent discoveries by CPCM researchers include mechanisms that cancer cells use to repair chemotherapy damage that should have killed them, to hide from drugs in protected “niches” in the body, or to grow when and where they should not.
CPCM members are also working on a second research pillar, which involves finding ways to use existing FDA-approved cancer drugs more effectively, particularly in carefully designed combinations. Combination therapies are currently used in the clinic to treat some cancers, yet the discovery process for these has been largely empirical. By contrast, CPCM investigators are integrating their knowledge of cancer biology, understandings of drugs’ mechanisms of action, and sophisticated analytical techniques, to identify or design specific combinations that work synergistically to disarm and then destroy cancer cells.
“We believe we can significantly alter cancer patients’ outcomes by determining the right combination of therapies and the right sequence of drugs for the right patients,” says Yaffe. “We’re also concentrating on innovative ways to give these drugs, like time-staggered dosages and nanoparticle delivery.” He notes that, as part of their analyses of drugs and combination regimens currently administered in the clinic, CPCM members expect to identify combinations of drugs that are not as efficacious when given simultaneously as when given sequentially, at specific intervals. Yaffe stresses that these will be important findings that could help reduce the toxicity of treatment by not exposing people to multiple drug toxicities at the same time.
In parallel with their efforts to use existing drugs more effectively, CPCM investigators are also working to identify compounds, materials, and approaches that can engage key “undruggable” genetic and molecular targets and disrupt processes driving drug resistance. The “undruggable” label often refers to the fact that a target protein or molecule lacks a site to which drugs can bind, and thus is not considered a good drug target by the pharmaceutical industry. However, using novel chemistry approaches, CPCM researchers have made early inroads against several such high-value cancer targets, including specific transcription factors and RNA-binding proteins. The center will continue and expand these efforts as the third part of its research platform, including collaborations with industry.
Finally, the fourth component of the CPCM’s efforts will be harnessing MIT’s particular expertise in big data analysis and tools to begin new and expedite existing cancer research efforts. For example, the researchers plan to use data analytics to identify selective panels of biomarkers that can be used to prioritize which of their drug combinations, treatment protocols, and formulations are best suited to a particular patient’s tumor.
Getting discoveries out the door
“Patients will be the ultimate beneficiaries of the work of the new MIT Center for Precision Cancer Medicine,” says Tyler Jacks, director of the Koch Institute and the David H. Koch Professor of Biology. “This research is, by its nature, imminently and rapidly translatable. By concentrating efforts on which patients will benefit from particular existing drugs or combinations of drugs, there is a relatively small step from laboratory to a treatment that is benefitting a cancer patient.”
While work on combinations of approved therapies, like that at the CPCM, may be more rapidly translatable than other cancer research, it can be challenging for industry to pursue, particularly when those drugs hail from multiple companies. Overcoming this disjuncture is one of the goals behind the establishment of the MIT Center for Precision Cancer Medicine, which was made possible by a generous gift from an anonymous donor.
Yaffe and his CPCM colleagues are committed to finding viable routes to move their cancer research into the clinic, particularly through collaborations between CPCM members, hospitals, and industry. Logistically, this means more work for the center’s research groups, including advanced laboratory and preclinical studies, safety and scale-up studies, and clinical-grade manufacturing, as well as staff to carry it out. Woven into these efforts, CPCM investigators will tap into MIT’s celebrated tradition of entrepreneurship and, even more so, the Institute’s expanding network of clinical collaborators. The philanthropic investment behind the center will provide stable financial support for the researchers’ endeavors.
The new hub in town
In addition to supporting the research of member investigators, the CPCM offers a robust training ground for young engineers and scientists interested in precision medicine. Moreover, it will serve as the hub of precision cancer medicine research at MIT and beyond, connecting with researchers across the MIT campus and partnering with clinical investigators in Greater Boston’s noted health care centers and around the country.
Five outstanding cancer researchers make up the center’s founding faculty:
Michael B. Yaffe, MD, PhD, director, MIT Center for Precision Cancer Medicine; David H. Koch Professor of Science, professor of biology and biological engineering
Efforts are currently underway to recruit an assistant director and a scientific advisory board.
As part of its charge, and key to spurring the new collaborations in precision cancer medicine that are its focus, the MIT Center for Precision Cancer Medicine will also convene lectures, events, and scientific exchanges and symposia, the first of which is slated for the fall.
Department of Biology kicks off IAP seminar series with a lecture by synthetic-biology visionary George Church.
Raleigh McElvery | Department of Biology
January 31, 2018
Thanks to the invention of genome sequencing technology more than three decades ago, we can now read the genetic blueprint of virtually any organism. After the ability to read came the ability to edit — adding, subtracting, and eventually altering DNA wherever we saw fit. And yet, for George Church, a professor at Harvard Medical School, associate member of the Broad Institute, and founding core faculty and lead for synthetic biology at the Wyss Institute — who co-pioneered direct genome sequencing in 1984 — the ultimate goal is not just to read and edit, but also to write.
What if you could engineer a cell resistant to all viruses, even the ones it hadn’t yet encountered? What if you could grow your own liver in a pig to replace the faulty one you were born with? What if you could grow an entire brain in a dish? In his lecture on Jan. 24 — which opened the Department of Biology’s Independent Activities Period (IAP) seminar series, Biology at Transformative Frontiers — Church promised all this and more.
“We began by dividing the Biology IAP events into two tracks: one related to careers in academia and another equivalent track for industry,” says Jing-Ke Weng, assistant professor and IAP faculty coordinator for the department. “But then it became clear that George Church, Patrick Brown, and other speakers we hoped to invite blurred the boundaries between those two tracks. The Biology at Transformative Frontiers seminar series became about the interface of these trajectories, and how transferring technologies from lab bench to market is altering society as we know it.”
The seminar series is a staple in the Department of Biology’s IAP program, but during the past several years it has been oriented more toward quantitative biology. Weng recalls these talks as being relegated to the academic sphere, and wanted to show students that the lines between academia, industry, and scientific communication are actually quite porous.
“We chose George Church to kick off the series because he’s been in synthetic biology for a long time, and continues to have a successful academic career even while starting so many companies,” says Weng.
Church’s genomic sequencing methods inspired the Human Genome Project in 1984 and resulted in the first commercial genome sequence (the bacterium Helicobacter pylori) 10 years later. He also serves as the director of the Personal Genome Project, the “Wikipedia” of open-access human genomic data. Beyond these ventures, he’s known for his work on barcoding, DNA assembly from chips, genome editing, and stem cell engineering.
He’s also the same George Church who converted the book he co-authored with Ed Regis, “Regenesis: How Synthetic Biology Will Reinvent Nature and Ourselves,” into a four-letter code based on the four DNA nucleotides (A, T, C, and G), subsisted on nutrient broth from a lab vendor for an entire year, and dreams of eventually resurrecting woolly mammoths. He’s being featured in an upcoming Netflix Original documentary, so when he arrived at the Stata Center to give his lecture last week he was trailed by a camera crew.
According to Church, the transformative technologies that initially allowed us to read and edit DNA have grown exponentially in recent years with the invention of molecular multiplexing and CRISPR-Cas9 (think Moore’s Law but even more exaggerated). But there’s always room for improvement.
“There’s been a little obsession with CRISPR-Cas9s and other CRISPRs,” said Church. “Everybody is saying how great it is, but it’s important to say what’s wrong with it as well, because that tells us where we’re going next and how to improve on it.”
He outlined several of his own collaborations, including those aimed at devising more precise methods of genome editing, one resulting in 321 changes to the Escherichia coli genome — the largest change in any genome yet — rendering the bacterium resistant to all viruses, even those it had not yet come into contact with. The next step? Making similarly widespread changes in plants, animals, and eventually perhaps even human tissue. In fact, Church and his team have set their sights on combatting the global transplantation crisis with humanlike organs grown in animals.
“Since the dawn of transplantation as a medical practice, we’ve had to use either identical twins or rare matches that are very compatible immunologically, because we couldn’t engineer the donor or the recipient,” said Church.
Since it’s clearly unethical to engineer human donors, Church reasoned, why not engineer animals with compatible organs instead? Pigs, to be exact, since most of their organs are comparable in size and function to our own.
“This is an old dream; I didn’t originate it,” said Church. “It started about 20 years ago, and the pioneers of this field worked on it for a while, but dropped it largely because the number of changes to the genome were daunting, and there was a concern that the viruses all pigs make — retroviruses — would be released and infect the immunocompromised organ recipient.”
Church and his team successfully disrupted 62 of these retroviruses in pig cells back in 2015, and in 2017 they used these cells to generate living, healthy pigs. Today, the pigs are thriving and rearing piglets of their own. Church is also considering the prospect of growing augmented organs in pigs for human transplantation, perhaps designing pathogen-, cancer-, and age-resistant organs suitable for cryopreservation.
“Hopefully we’ll be doing nonhuman primate trials within a couple of years, and then almost immediately after that human trials,” he said.
Another possibility, rather than cultivating organs in animals for transplant, is to generate them in a dish. A subset of Church’s team is working on growing from scratch what is arguably the most complicated organ of all, the brain.
This requires differentiating multiple types of cells in the same dish so they can interact with each other to form the complex systems of communication characteristic of the human brain.
Early attempts at fashioning brain organoids often lacked capillaries to distribute oxygen and nutrients (roughly one capillary for each of the 86 billion neurons in the human brain). However, thanks to their new human transcription factor library, Church and colleagues have begun to generate the cell types necessary to create such capillaries, plus the scaffolding needed to promote the three-dimensional organization of these and additional brain structures. Church and his team have not only successfully integrated the structures with one another, but have also created an algorithm that spits out the list of molecular ingredients required to generate each cell type.
Church noted these de novo organoids are extremely useful in determining which genetic variants are responsible for certain diseases. For instance, you could sequence a patient’s genome and then create an entire organoid with the mutation in question to test whether it was the root cause of the condition.
“I’m still stunned by the breadth of projects and approaches that he’s running simultaneously,” says Emma Kowal, a second-year graduate student, member of Weng’s planning committee, and a former researcher in Church’s lab. “The seminar series is called Biology at Transformative Frontiers, and George is very much a visionary, so we thought it would be a great way to start things off.”
The four-part series also features Melissa Moore, chief scientific officer of the Moderna Therapeutics mRNA Research Platform, Jay Bradner, president of the Novartis Institutes for BioMedical Research, and Patrick Brown, CEO and founder of Impossible Foods.
Sixth year graduate student Zoë Hilbert investigates how C. elegans react to changes in their environment — and how these changes affect physiology, gene expression, and behavior
Raleigh McElvery
January 30, 2018
Sixth year graduate student Zoë Hilbert is sure of many things. After performing her first dissection in third grade, she was sure she liked science. Before she started college, she was sure she wanted to major in a biology-related discipline. And as she finished her final year at Columbia University, she was sure she would leave the East Coast immediately upon graduation. What she did not anticipate, however, was falling in love with the Cambridge biotechnology hub, applying to MIT for graduate school, and switching fields from biochemistry to genetics.
“I’m incredibly grateful for the MIT first-year program, because dedicating the fall semester solely to taking classes gave me a background in subjects I didn’t take in college,” Hilbert says. “I’d never taken genetics before, and now here I am in Dennis Kim’s lab — a genetics lab.”
Hilbert was enthralled by evolution from an early age, in particular the idea that entire organisms and their proteins change over time in response to internal and external pressures. She recalls becoming “obsessed” with the small and seemingly unremarkable stickleback fish, after she learned that researchers could map the evolution of physical features like additional belly fins or extra armor to variations in specific genes.
“When it came time for the first years to write our National Science Foundation proposals, we had the opportunity to work with a faculty member,” she recalls, “and I chose Dennis because one of the project ideas he’d listed was in a similar vein to the stickleback research. Coming into it, I didn’t know anything about his work or even his model system, but I ended up joining the lab after second semester rotations.”
The Kim lab investigates how the roundworm Caenorhabditis elegans reacts to changes in their environment — and how these changes not only affect physiology and gene expression, but behavior as well.
Today, Hilbert is as enamored by C. elegans as she once was with stickleback fish. With minimal prodding, she’s happy to rattle off their numerous advantages: they’re transparent, so there’s no need to do dissections to look inside; they’re ideal for studying development and the nervous system, because scientists have already charted all the cells in the body and how the neurons communicate; and they’re low-maintenance and easy to keep in lab. The list goes on.
But most pertinent to Hilbert is the fact that — like most species of animals — the two sexes of C. elegans, males and hermaphrodites, often behave differently in similar situations due to differences in gene expression. Take mating, for example.
Hermaphrodites are capable of self-fertilization, and can produce up to several hundred identical progeny over the course of several days. Males are much less common and unable to reproduce on their own, but by mating with hermaphrodites they can introduce some genetic variety into their offspring. Because males must locate a hermaphrodite in order to pass on their genetic material, they’ve developed some specific behaviors to find their mate. And that’s where Hilbert’s work comes in. She makes males choose between the two things they need most: food and mate.
There comes a time in every adult male’s life when finding a mate takes precedence over continuously eating, as younger worms are wont to do. If he is placed in a plate of yummy bacteria by himself, he runs away — not because he’s full, but because he’d rather spend his time searching for a mate. However, if he is placed in a plate of food along with a tempting hermaphrodite, his urge to escape is suppressed and he remains long enough to mate.
That said, C. elegans mating is not always so cut and dry. Researchers understand that a male’s behavior is also food-dependent. If you place a starving male on the plate of food, he no longer prioritizes mating over feeding, and will remain in the food instead of seeking a mate. He is constantly evaluating his priorities, which are heavily influenced by the situation at hand and — as Hilbert discovered — when and where certain genes are expressed.
“We’ve spent a lot of time monitoring how the expression of daf-7 changes in different food and mating situations,” Hilbert says. “When you starve the male, you suppress the gene and as a result you also suppress the fleeing behavior.”Hilbert demonstrated several years ago that this male-specific behavior is controlled by a gene known as daf-7, which encodes a signaling molecule and is expressed in two specific neurons in the male. (No expression is normally seen in the hermaphrodite.) Curiously, the same gene in the same two neurons is also turned on when any worm — male or hermaphrodite — comes across a pathogen, sending a “WARNING: consume at your own risk” signal, and prompting the worm to avoid the noxious bacteria.
Expression appears to be dependent not only on nutritional state (hungry or full), but also environment (food and/or mate) and sex (since males express daf-7 differently than hermaphrodites).
“All these factors and signals are converging on this one gene,” Hilbert says. “It’s really quite incredible.”
The neurons that express daf-7 are “sensory,” and traditionally viewed as funnels to higher neural centers where information is processed and behaviors are generated. However, Hilbert’s data suggest this information processing is happening right there, directly within these neurons via changes in gene expression without waiting for instructions from on high.
What Hilbert finds particularly intriguing is that the worms rely on just one molecular pathway to dictate behavior in two very different situations: mating and pathogen avoidance. Although the worm flees food in both situations, precisely why one gene is implicated in two distinct settings remains a mystery. Hilbert is still asking herself, For what benefit?
She intends to spend her final semester at MIT tying up loose ends and conducting follow-up experiments to extend the work from her recent paper in the January 2017 issue of eLife, on which she was first author. She’s screening for molecules that could impact whether or not daf-7 is expressed, honing in on chemicals and signaling molecules used by neurons to communicate with one another.
“I’d advise prospective grads to be willing and open to change your mind about what you want to do,” she says. “I was really into protein biochemistry when I first arrived at MIT, and was really surprised when I fell in love with a discipline that was completely different from my initial interests.”
As Hilbert applies to academic postdoctoral positions, she’s still set on fulfilling her longtime dream of heading out West. She’s sure she’d like to end up someplace like California, Washington, or Utah, but only time will tell.
Photo credit: Raleigh McElvery
Study explains why mutations that would seemingly affect all cells lead to face-specific birth defects.
Anne Trafton | MIT News Office
January 24, 2018
About 1 in 750 babies born in the United States has some kind of craniofacial malformation, accounting for about one-third of all birth defects.
Many of these craniofacial disorders arise from mutations of “housekeeping” genes, so called because they are required for basic functions such as building proteins or copying DNA. All cells in the body require these housekeeping genes, so scientists have long wondered why these mutations would produce defects specifically in facial tissues.
Researchers at MIT and Stanford University have now discovered how one such mutation leads to the facial malformations seen in Treacher-Collins Syndrome, a disorder that affects between 1 in 25,000 and 1 in 50,000 babies and produces underdeveloped facial bones, especially in the jaw and cheek.
The team found that embryonic cells that form the face are more sensitive to the mutation because they more readily activate a pathway that induces cell death in response to stress. This pathway is mediated by a protein called p53. The new findings mark the first time that scientists have determined how mutations in housekeeping genes can have tissue-specific effects during embryonic development.
“We were able to narrow down, at the molecular level, how issues with general regulators that are used to make ribosomes in all cells lead to defects in specific cell types,” says Eliezer Calo, an MIT assistant professor of biology and the lead author of the study.
Joanna Wysocka, a professor of chemical and systems biology at Stanford University, is the senior author of the study, which appears in the Jan. 24 online edition of Nature.
From mutation to disease
Treacher-Collins Syndrome is caused by mutations in genes that code for proteins required for the assembly and function of polymerases. These proteins, known as TCOF1, POLR1C, and POLR1D, are responsible for transcribing genes that make up cell organelles called ribosomes. Ribosomes are critical to all cells.
“The question we were trying to understand is, how is it that when all cells in the body need ribosomes to function, mutations in components that are required for making the ribosomes lead to craniofacial disorders? In these conditions, you would expect that all the cell types of the body would be equally affected, but that’s not the case,” Calo says.
During embryonic development, these mutations specifically affect a type of embryonic cells known as cranial neural crest cells, which form the face. The researchers already knew that the mutations disrupt the formation of ribosomes, but they didn’t know exactly how this happens. To investigate that process, the researchers engineered larvae of zebrafish and of an aquatic frog known as Xenopus to express proteins harboring those mutations.
Their experiments revealed that the mutations lead to impairment in the function of an enzyme called DDX21. When DDX21 dissociates from DNA, the genes that encode ribosomal proteins do not get transcribed, so ribosomes are missing key components and can’t function normally. However, this DDX21 loss only appears to happen in cells that are highly sensitive to p53 activation, including cranial neural crest cells. These cells then undergo programmed cell death, which leads to the facial malformations seen in Treacher-Collins Syndrome, Calo says.
Other embryonic cells, including other types of neural crest cells, which form nerves and other parts of the body such as connective tissue, are not affected by the loss of DDX21.
Role of DNA damage
The researchers also found that mutations of POLR1C and POLR1D also cause damage to stretches of DNA that encode some of the RNA molecules that make up ribosomes. The amount of DNA damage correlated closely with the severity of malformations seen in individual larvae, and mutations in POLR1C led to far more DNA damage than mutations in POLR1D. The researchers believe these differences in DNA damage may explain why the severity of Treacher-Collins Syndrome can vary widely among individuals.
Calo’s lab is now studying why affected cells experience greater levels of DNA damage in those particular sequences. The researchers are also looking for compounds that could potentially prevent craniofacial defects by making the cranial neural crest cells more resistant to p53-induced cell death. Such interventions could have a big impact but would have to be targeted very early in embryonic development, as the cranial neural crest cells begin forming the tissue layers that will become the face at about three weeks of development in human embryos.
The research was funded by the National Institutes of Health, Howard Hughes Medical Institute, and March of Dimes Foundation.
December 14, 2017
Lab coat meets legislation
Undergraduate Courtney Diamond combines biology and policy to tackle real-world challenges
Raleigh McElvery
Undergraduate Courtney Diamond arrived at MIT determined to be an oncologist. Five years later, she’s leaving with a broader focus on human health, grappling with real-world, biomedical problems by way of public policy rather than medicine or research.
Although Diamond had completed her requirements for a degree in biology at the beginning of her senior year, she decided then to add a second major: Course 17 (Political Science), and with it a fifth year of study at MIT.
“I came into MIT wanting to be a doctor, but the more I thought about it the less it felt like medical school would be a good fit,” she says. “I spent a long time narrowing my interests within the realm of human health, and recently realized there was another dimension to that interest related to public policy, which was also this common thread among my extracurriculars.”
Diamond grew up in a small town in Massachusetts called Millbury, not too far from MIT, which she describes as special to her but “rather unremarkable” in most other ways — with the exception of one particularly zealous and articulate high school biology teacher. His infectious enthusiasm sparked Diamond’s passion for the life sciences, but over the course of her senior year this interest became far more personal. It was around that time that her mother developed breast cancer, and Diamond resolved to be an oncologist.
“My mom had been diagnosed once before with a different kind of cancer, cervical cancer,” she says. “But I was in sixth grade back then, and assumed she was just at home resting. By the time the breast cancer rolled around, I was old enough to understand that most people are lucky to survive cancer once. But twice?”
Her mother has since entered remission, and the year Diamond began at MIT her interests matured away from a career in medicine and towards biomedical research. In April 2014, she applied to the MIT Undergraduate Research Opportunities Program (UROP). “I wanted to figure out which part of biology excited me — which area I really wanted to drill down on,” she recalls.
She began working with a postdoctoral fellow in Professor Darrell Irvine’s lab at the Koch Institute for Integrative Cancer Research, tackling research questions related to cancer immunology. Diamond’s job was to analyze murine tumors as they developed over time, in order to understand how they were affected by changes to their cellular environments.
After a year, Diamond took a break from research in order to focus on her classes. But she didn’t stay away for long.
“I’ve had a life-long obsession with Australia,” she says, “and in the fall of my sophomore year, I told my advisor, Professor Bob Horvitz, that my dream was to study biochemistry in Melbourne.” One email and two hours later, she received an offer from theWalter and Eliza Hall Institute for Medical Research to spend a summer abroad in Jeff Babon’s lab. “It turns out the director of the Institute did his postdoc at MIT, and liked the UROP system so much he decided to bring it back to Australia,” she explains.
There, Diamond helped to unravel the structure of a protein complex known as JAK-STAT. This complex is involved in many diverse processes — from cell proliferation and programmed cell death to immunity — making it critical to understand how the different molecular components of the complex fit together to influence function.
When she returned to MIT, Diamond decided to maintain her focus on structural biology. She completed her thesis in Professor Thomas Schwartz’s lab, studying the Y complex, a component of the nuclear pore — a channel that allows mRNA and other molecules to pass into the cell’s nucleus. Diamond helped creat a library of fluorescing antibodies that could adhere to the Y complex, allowing her to visualize its position within the nuclear pore. After a year, she opted to broaden her interests by taking classes outside her major.
One of those classes, recommended by a friend, was in political science: 17.309 (Science, Technology, and Public Policy), taught by Professor Kenneth Oye. During one of his lectures, Oye made a quip about a small Massachusetts town called Millbury.
“I came up to him after class to ask him, ‘Did you know I’m actually from there?’ and he thought it was the funniest thing,” she says. “That initial, informal interaction led to more meaningful conversations, and I ended up working with him on a few projects.”
Today, she is pursuing a final UROP with Oye, looking at technologies and policies related to synthetic biology. At Oye’s weekly working group of graduate students and postdocs, she debates the possible repercussions of using gene editing techniques like CRISPR-Cas9 to control the transmission of certain traits throughout a given population. For example, what would happen if mosquitos in the regions where malaria is most prevalent carried a gene encoding malaria resistance — would that eradicate the illness? But might there be unintended, negative consequences?
As part of a separate project, Diamond is researching U.S. consent and privacy policies in the realm of health information technology. She’s also hard at work on her political science thesis, focusing on ways to incentivize companies and researchers to develop new and more effective antibiotics to combat antimicrobial resistance.
Diamond is now applying for public health consulting jobs, and she plans to pursue graduate training in epidemiology, followed by a master’s in public health. Long-term, she sees herself at theCenters for Disease Control and Prevention or the World Health Organization.
“I mean, that’s the current plan,” she says. “Check back in with me in two years.”
Photo credit: Raleigh McElvery
Carolyn Lanzkron discovered bench science while attending community college with her son, and followed her newfound passion to MIT
Raleigh McElvery
December 3, 2017
From DNA forensics to cancer metabolism
Carolyn Lanzkron discovered bench science while attending community college with her son, and followed her newfound passion to MIT
Raleigh McElvery
Carolyn Lanzkron spent 20 years as a stay-at-home mother raising five children before starting at MIT. Life has taught her patience, which she, in turn, has tried to pass on to her kids: “A successful person falls down many times and gets up — just pick a direction and move forward.”
Those were the same words she told her teenage son back in 2011 when she encouraged him to attend community college.
“I figured I would just take a few courses with him,” she says. “He enjoyed his chemistry classes, so I was looking at the chemistry offerings, and on the wall there was a poster for Dr. Bruce Jackson’s unique Forensic DNA Science program.” Lanzkron was intrigued, and decided to enroll.
The students aided Jackson with real cases, and were given dedicated lab space and materials to follow their curiosities, as well as design their own inquiries. The program was based on a peer-mentoring model, and Lanzkron was appointed chief of peer mentors and forensic case manager. Under Jackson’s tutelage, she worked on lineage cases tracing ancestry and criminal cases for defense and prosecution.
“I was hoping my son would join me in a chemistry class, but he wasn’t so interested in having his mom as a lab partner — go figure,” she says. “But we carpooled to school together for a year, and by that time I’d developed a love for bench science.”
After two years, Lanzkron had completed her degree, but it wasn’t enough. So she applied to several institutions within her carpool radius, including MIT. Like all transfers here, she began as a sophomore.
“I love bench science because I really appreciate the combination of being part of a team and solving a big, important question, but at the same time having tasks in my day that allow me to focus on small details — like keeping track of the labels on my tubes,” she says. “That balance works really well for me; it satisfies my need for a quest while still having control over a small environment.”
She’s turned her attention from DNA forensics to cancer metabolism, an interest which has become far more personal over the past year. Last spring, Lanzkron’s mother was diagnosed with lung cancer, and Lanzkron took a leave of absence to care for her.
“Right now, my mother is doing really well, and we are enjoying a window of stability,” Lanzkron says, “which has allowed me to come back to MIT and finish my degree.”
Although Lanzkron is not currently in a lab, lest that period of stability suddenly end, she’s worked in several over the course of her three years at MIT. She began in Jean Francois Hamel’s chemical engineering lab, adapting an adherent cell line to grow in a suspension-like culture in various bioreactors using microcarriers.
Later, Lanzkron joined David Sabatini’s lab in the Whitehead Institute for Biomedical Research, aiding two separate projects: one spearheaded by then-postdoc Yoav Shaul, and the other led by MD-PhD student Walter Chen.
Chen was hard at work developing a new method for profiling undamaged mitochondria, while Shaul had discovered a unique set of 44 metabolic genes that were upregulated in certain cancers that expressed mesenchymal markers (which he called the “Mesenchymal Metabolic Signature,” or “MMS”), indicating that those cells were acquiring cancerous characteristics. Lanzkron collaborated with Shaul as he worked to further characterize the metabolic requirements and behavior of the MMS. She also helped him refine his web-based gene analysis tool, Metabolic gEne RApid Visualizer (MERAV), which queries a database comprising ∼4,400 microarrays, representing human gene expression in normal tissues, cancer cell lines, and primary tumors.
The summer after Shaul completed his postdoctoral training, Lanzkron interned in his lab in at the Hebrew University of Jerusalem at Hadassah Ein Kerem through the MISTI/Israel program, to continue working with him on these projects.
“When I went to Israel, my husband stayed in Boston and took care of the kids,” she recalls. “Without family responsibilities, I could work in lab around the clock, and that was great. I was actually able to finish things up, prepare them for the next day, and cover for other people and really focus; I look forward to being able to do that again as the kids get older.”
Lanzkron admits these aren’t the only aspects of the MIT undergraduate experience she’s missed — not just because she lives off campus and can’t meet at odd hours of the night to collaborate on problem sets — but also because she’s a generation and a half older than her classmates.
But in some ways she considers this an advantage. For instance, she now has the tools to guide her own children through today’s college process.
“I no longer have this outdated view of what it’s like to apply to schools and navigate the SAT,” she says. “Granted, MIT is not your average school. It’s been quite the ride to be at the community college where I had to bring my own masking tape to complete the gel trays because we didn’t have any sealing rings — I didn’t even know there was such a thing as a seal back then. And to go from that to the MIT Department of Biology and the Whitehead Institute where the resources are phenomenal, it’s just mind blowing. I have learned so much from both situations — having to make do, and having an abundance of resources.”
While Lanzkron intends to graduate this spring, her future plans depend on her mother’s health.
“I picked my classes this semester so that I could take her to her cancer treatment,” Lanzkron says, “so, though I’m ultimately planning to go to graduate school, right now things are still in flux.”
While maintaining this school-family balance would be inconceivable for most, Lanzkron takes her personal and academic responsibilities in stride.
“Honestly I’m so happy here at MIT,” she says. “I tell my kids, ‘Don’t get too worked up about the college process. You’ll get where you need to go — the starting point almost doesn’t matter; what matters is what you do when you get there.’”
Photo credit: Raleigh McElvery
Undergraduate Camilo Espinosa grew up with a love for math, before developing a second passion for immunology at MIT
Raleigh McElvery
November 10, 2017
Biology by Numbers
Undergraduate Camilo Espinosa grew up with a love for math, before developing a second passion for immunology at MIT
Raleigh McElvery
Undergraduate Camilo Espinosa, now in his senior year, tackles biological problems with the mindset of a mathematician. That’s because he initially approached the STEM fields (science, technology, engineering and mathematics) starting with the “M” and ending with the “S” — developing an appetite for math before realizing a second love for biology.
Every six months, beginning his first year of middle school, Espinosa would venture from his home on the north coast of Colombia to the nation’s capital. There, for several weeks, he would do nothing but math.
“These were math olympiads — basically a combination of math camp and competitions,” he explains. “That was the first real community I had outside my school.”
But he didn’t just glean formulas and analytical strategies from those competitions; it was his olympiad team that first introduced him to MIT. In Colombia, he explains, students must select a major almost immediately upon entering university, and are offered limited electives. MIT came to represent “academic freedom” for Espinosa, who, despite his avid and early love of math, intended to explore multiple academic avenues before limiting himself to just one.
Now, as a math and chemistry-biology double major with a concentration in philosophy, he says MIT has enabled him to pursue his many academic interests, as well as his non-academic ones. He has served as an active member of not one but four dance teams, as well as president of his fraternity. He also helped establish a channel of communication between the International Students Office and the Department of Biology, to streamline the work authorization process for international students.
He was drawn to biology, he explains, because he prefers learning processes over basic facts. “I don’t care much for memorization, but I do care about the underlying reasons for why and how things function,” he says. “I think that mindset stems from my dad.”
Espinosa’s father is an OB/GYN specializing in female oncology, who initially helped to popularize laparoscopic surgery techniques in Colombia. Often, he sees patients at a discounted price or for free if they could not afford his services.
“At the end of the day, he is just trying to help people,” Espinosa explains. “He taught me the way I think about the world. He’s the reason I do what I do, and why I’m so oriented towards the life sciences.”
Espinosa’s siblings are studying to become doctors and veterinarians, and he himself is intrigued by the possibilities of using our body’s innate defense mechanisms to treat diseases like cancer.
His foray into the field of immunology began with antibodies — special ones taken from furry, gawky alpacas — so tiny and versatile that they can be employed for all manner of imaging, therapeutic, and diagnostic techniques. These “single domain” antibodies were a popular area of interest in Hidde Ploegh’s lab (formerly a Professor of Biology at the Whitehead Institute for Biomedical Research), where Espinosa began mid-way through October of his freshman year. Using these single-domain antibodies, the Ploegh lab had developed a treatment for melanoma in mice, and Espinosa worked to pinpoint antibodies directed against melanoma in humans.
The summer between his sophomore and junior years, Espinosa began a separate project that eventually evolved into his thesis. He honed in on one tiny antibody, known as A4, which binds to a particular protein expressed on the surface of red blood cells, and has the potential to thwart the immune response by activating a process known as “tolerance.”
Our body’s immune system is programmed to discern self from non-self, targeting foreign entities for destruction. It does so in two distinct steps. First, it creates an army of cells, that together express antibodies tailored to combat virtually every possible substance, both self and non-self. The immune system is then primed to spring into action whenever it senses something foreign, amplifying those cells that express antibodies against it. However, the body would also attack itself if not for the second step in this process: tolerance. The immune system essentially deletes the cells expressing antibodies against itself, and in doing so learns to “tolerate” its own proteins.
For example, when red blood cells die of old age (and many do every day), this triggers tolerance to the various protein components that constitute those cells — preventing related antibodies from being created.
Previous work has shown that binding a foreign protein to red blood cells triggers tolerance for that specific protein, despite being “non-self.” This could have implications for therapies to treat conditions like hemophilia, Espinosa explains, which require injections of proteins to reinstate the body’s blood-clotting abilities.
In a large proportion of patients, the immune system responds and attacks these proteins as foreign, rendering the treatment useless and barring the patients from receiving it again in the future. However, Espinosa proposes, if he could couple A4 to the treatment protein, then A4 would link the protein to the red blood cells and initiate tolerance to it. Since the body can no longer create antibodies against the treatment proteins, the therapy can run its course. In other words, the body would now see the injected proteins as self.
After months of methodical experiments, A4 didn’t appear to disguise proteins as self in the way Espinosa had initially hoped, although it did reduce the immune response triggered by the protein injection, if he staggered the protein and antibody infusions in the proper manner.
“So maybe A4 doesn’t work as a camouflage per se, but rather as a suppressor of certain immune responses,” he says. “So the results didn’t turn out exactly as we expected, but it is still a step in the right direction.”
He ultimately submitted his thesis to MIT’s Ilona Karmel Writing Prizes,earning second place in the technical writing category.
Last summer, Espinosa explored a different side of basic research — the corporate side — during an internship at the biotechnology company Genentech. There, he investigated the pathways by which uncontrolled cell death leads to sepsis in patients.
As he wraps up his senior year and begins applying to graduate programs, Espinosa reflects on his transition from student to instructor, having served as a teaching assistant in a number of biology courses during the past three years. “As someone who arrived at MIT with a weak foundation in biology, almost everything I’ve learned since was because someone taught it to me, and taught it to me well,” he says. “I feel honored to be able to pass it on.”
Photo credit: Raleigh McElvery
Posted: 1.18.18
Graduate student Zhaoqi Li investigates how cancer cells grow by harnessing exceptional chemical reactions
Justin Chen
January 11, 2018
Cancer cells use extreme measures to fuel their growth. In fact, researchers like Zhaoqi Li, a third-year graduate student, witness chemical reactions in these cells that would be impossible in the context of normal cells. In a petri dish, normal cells stop dividing once they cover the bottom of the dish and fit neatly together like mosaic tiles. In contrast, cancer cells continue to proliferate and pile haphazardly into small mounds. Within the human body, this abnormal growth — when combined with the spread of cancer cells throughout the body — interferes with organ function and causes death.
Li, a member of Professor Matthew Vander Heiden’s lab located in the Koch Institute, studies cancer metabolism. His work describes the chemical reactions cancer cells use to create energy and materials to make new cells such as membranes, proteins, and DNA. By tracking the flow of nutrients through cancer cells, Li and his labmates are learning how such cells change their metabolism to stimulate growth. These insights will help scientists develop new ways to treat the disease.
Cell metabolism comprises all the chemical reactions occurring in the cell, but researchers are particularly interested in a few reactions that aren’t required by normal cells but are critical for cancer growth. Stopping these reactions with drugs would disrupt the metabolism of cancer cells and hinder tumor development.
“Even though many people may not think of metabolism as a treatment target for cancer, this strategy has been used unwittingly for a long time,” Li says. “Many chemotherapies, such as antifolates, were originally used by doctors without knowing exactly how they worked. Since then, we’ve discovered that those treatments target metabolic pathways. By understanding the details of cancer metabolism we are hoping to design drugs in a more rational way.”
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Li might never have joined the Vander Heiden lab or studied cancer metabolism were it not for the unique structure of graduate training at MIT.
During their first year at MIT, graduate students are required to take four classes. Unlike their counterparts at many other PhD programs, they do not work in laboratories until their second semester. This allows students to focus initially on coursework — covering biochemistry, genetics, and research methodology — designed to build a foundation of knowledge. As a result, students discover new interests and develop the confidence to move out of their comfort zones. When it comes time to select a lab, they can choose from 56 spread across six locations, spanning a wide breadth of biological research.
Li could study how the brain forms memories, interpret X-rays to deduce protein structure, or even build miniature organs for drug testing. Before making his decision, he rotated in three laboratories. During each month-long rotation, he performed a small project allowing him to experience the culture of the lab and learn more about its research.
“The first two labs I visited were studying topics I was familiar with and thought were interesting,” he says. “But when I visited the Vander Heiden lab it was so different and caught me off guard. That’s why I eventually joined, even though I had never imagined myself working in a metabolism lab before.”
Cellular metabolism is comprised of a network of interconnected biochemical reactions resembling a subway system. Zhaoqi Li compares normal and diseased cells to determine the differences in the way nutrients travel through this network. Credit: Justin Chen
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Although he is new to the community of researchers specializing in metabolism, Li has long known that he wanted to interact with the world through science. As an immigrant who moved from China to southern Tennessee at the age of six, Li struggled to learn English and began to view science as a universal language that transcended culture.
“My parents were also non-native speakers and the English as a Second Language classes in my elementary school were geared towards Spanish speakers, so I had a really hard time,” Li says. “I joke that the only reason I passed the first grade was because I was good at math.”
Li’s contrasting relationship with science and English continued as an undergraduate at Columbia University. There he majored in biochemistry and also studied literature of the Western Canon to fulfill his general degree requirements.
“I took four semesters worth of classes that started with Plato and ended with Virginia Woolf,” he says, “It was an eye-opening experience, but I never really loved it. I found biology more intuitive because it doesn’t rely on being familiar with a specific cultural lens. Most every society in the world values the scientific method to some extent.”
Li began working in a lab during his sophomore year at Columbia. To his surprise, he was mentored by a professor who valued his input and encouraged creative thinking. Li’s supervisor also introduced him to basic science — a type of research driven not by the desire to find a specific answer or cure, but by curiosity and the need to better understand the natural world.
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During his second semester rotation at MIT, Li searched for similarly open-minded environments, and was attracted to cancer metabolism because the field was relatively young.
“In other more established areas of biology, if you have a question someone has probably answered it in some capacity,” Li says. “The Vander Heiden lab was using new techniques so there was a lot of space to explore. Many questions I asked — even during my initial rotation — didn’t have an answer, which was exciting.”
The great challenge confronting the metabolism field is translating decades’ worth of research on enzymes — proteins that manage chemical reactions — from the test tube to the cell and human body. By studying enzymes individually in the controlled setting of test tubes, researchers have documented almost all the chemical reactions that occur in the cell. When combined, these reactions look like a giant subway map where each stop, indicated by a dot, is a different molecule, and the line between stops represents a chemical reaction where atoms are added or subtracted. Some pathways are a straight line but others have nodes or intersections where a molecule can take part in several different reactions. Other pathways are circular where the molecule that starts the pathway is remade at the end so that the line circles back on itself.
Despite the ability to study chemical reactions in a test tube, scientists have struggled to understand what is actually happening in the complex environment of cells, which coordinate millions of reactions that not only affect each other, but are also influenced by outside stresses like nutrient deprivation.
To Li, using the metabolism map to figure out what chemical reactions are occurring and how atoms are moving through the cell is like using a subway map to track how people are traveling through a city.
“The map describes all the possible routes people could take,” Li says, “but you have to track the passengers to figure out where they are actually going. You could imagine people commuting into the city during the week and going to entirely different places on the weekend. There are a lot of different patterns of movement that you can’t infer just from looking at a map.”
To analyze what chemical reactions are occurring in the cell, Li utilizes cutting edge technology to track carbon atoms — an essential element that is required to build all components of the cell. By tagging carbon with an extra neutron, Li makes the experimentally altered atom heavier and distinguishable from naturally occurring carbon in the cell. Feeding cells nutrients like glucose made with heavy carbons allows Li to compare how molecules are broken down and used by normal and cancerous cells.
“Returning to the subway map analogy, this labeling technique is similar to not only being inside the subway, but also giving everyone in Downtown Boston a red shirt,” Li says. “After 12 hours, we can look at the rest of the city. If we see a lot of red shirts in Allston, we would know that this particular route is really popular.”
In the case of glucose, Li and his labmates observed that normal cells break down the sugar to release energy and heavy carbons in the form of carbon dioxide. In contrast, cancer cells alter their metabolism so that the heavy carbons originally found in glucose are used to build new parts of the cells that are required for cancer cells to grow, such as membranes, DNA, and proteins.
Li’s observations demonstrate how cancer cells sustain abnormal growth by accumulating carbon. For his thesis project, Li has chosen to investigate one of the main tricks cancer cells use to hoard carbon atoms: a process known as carbon fixation. This type of chemical reaction, originally studied in plants performing photosynthesis, attaches carbon dioxide to other molecules. Li’s initial findings suggest that a protein, Malic Enzyme 1, helps cancer cells use carbon dioxide to build components required for growing and dividing.
“This is surprising,” he says, “because the textbook version of this enzyme actually catalyzes the reverse reaction in normal cells where carbon dioxide is removed from molecules. Malic Enzyme 1 is an example of how cancer performs remarkable chemical reactions — who would have thought that cancer cells use carbon like plants do?”
Li is at the beginning stages of his research, and can’t predict where his project will take him. His current goal is to determine how cancer cells react when they are missing Malic Enzyme 1. Such loss could slow growth, but Li will have to perform experiments to be sure, since cancer is a resourceful and elusive target.
Like a detour rerouting travelers around a closed metro stop, cancer cells may further contort their metabolism, taking advantage of little-used or still unidentified chemical reactions to maintain growth. In the face of such adaptability, Li and his labmates believe the best course of action is to be as curious as possible to understand as much as they can about how cancer works. Working together, they discuss confounding results, adjust hypotheses, and design new experiments.
“It’s really encouraging to be part of Matt’s lab and the Koch Institute in general where researchers take a basic science approach,” Li says. “We try to keep an open mind because there’s probably no single thing that cancer cells depend on. Everyone’s work builds together to form a cumulative understanding.”
Photo credit: Raleigh McElvery
Graduate student Faye-Marie Vassel investigates a protein that helps cells tolerate DNA damage, sharing her expertise with budding scientists to further STEM education
Raleigh McElvery
December 8, 2017
Combatting chemotherapy resistance
Graduate student Faye-Marie Vassel investigates a protein that helps cells tolerate DNA damage, sharing her expertise with budding scientists to further STEM education
Raleigh McElvery
Faye-Marie Vassel has a protein. Well, as a living entity, technically she has many, but just one she affectionately refers to as her own. “My protein, REV7.” And it makes sense — if you were hard at work characterizing a single protein for all six years of your graduate career, you’d be pretty attached, too. Plus, the stakes are high. REV7, which aids in DNA damage repair, could ultimately provide insight into ways to combat chemotherapy resistance.
Although Vassel’s mother trained as an OB/GYN in Russia before moving to the U.S., serving as what Vassel describes as a “quiet” scientific role model, Vassel spent her early childhood emulating her father, a social worker, and engrossed in the social sciences. She intended to one day work in science policy — until high school when she joined an after-school program at the American Museum of Natural History in New York City, and discovered an additional interest.
Here, Vassel took a series of molecular biology classes and met her first female research mentor, a postdoctoral fellow at Rockefeller University, who encouraged her to participate in another, more advanced science program funded by the National Science Foundation.
“I initially had my doubts, but just having that support changed everything,” Vassel says. “That was my first time doing research of any kind, and I got a sense of the sheer diversity of potential research projects. That’s also when I heard there was something called biophysics.”
From that point on, Vassel was hooked. As an undergraduate at Stony Brook University, she initially declared a major in physics before switching to biochemistry. Later, when it came time to select a graduate school, she was split between MIT and the University of California, Berkeley. As she recalls, MIT’s graduate preview weekend made all the difference.
“I had the chance to stay with biology students and speak with professors,” she says. “The whole experience made the department seem personal, and demystified the graduate school process by making it more tangible.”
She proposed a joint position between two labs: Graham Walker’s lab, based in Building 68, and Michael Hemann’s lab situated in the Koch Institute for Integrative Cancer Research. Walker’s lab focuses on microbiology, DNA repair, and antibiotic resistance, while Hemann’s lab investigates chemotherapy resistance in hopes of improving cancer therapies. After stumbling upon one of their joint papers, Vassel decided she’d like to combine the two.
“It’s invaluable to have both perspectives,” she says. “Mike’s lab just celebrated its 10th anniversary, while Graham‘s just had its 35th. It’s been interesting seeing the different ways they approach their respective research questions, because they were trained in such different scientific eras.”
Although Vassel is currently the only student formally working in both labs, the collaboration between Walker and Hemann, aimed at combatting chemotherapy resistance, has been ongoing.
Frontline chemotherapies, including one anticancer agent called cisplatin, kill cancer cells by damaging their DNA and preventing them from synthesizing new genetic material. Just how sensitive cancer cells are to cisplatin — and therefore how effective the treatment is — depends on whether the cell can repair the damage and bypass DNA-damage induced cell death. In some cases, cells increase production of “translesion polymerases,” which are specialized DNA polymerases that can help cells tolerate certain kinds of DNA damage by synthesizing across from damaged DNA or DNA bound to a carcinogen.
Vassel’s protein, REV7, is a structural subunit of one key translesion polymerase, and its expression is deregulated in many different cancer cells. As Vassel suggests, if one aspect of these translesion polymerases — say, the REV7 subunit — could be altered to hinder repair, then perhaps cancer-ridden cells could regain drug sensitivity.
Thanks to recently-developed CRISPR-Cas9 gene editing techniques, Vassel has removed REV7 entirely from drug resistant lung cancer cells, and watched as cisplatin sensitivity was restored. She also conducted rescue experiments, adding REV7 back into cell lines lacking the protein to see whether those cells become resistant to the drug once again. Most recently, she has been working in murine models to see whether REV7 has similar effects in a living system.
If her hypothesis is correct, REV7 would be a powerful target for drug development. Treatments that inhibit REV7, she explains, could be used in tandem with frontline chemotherapies like cisplatin to prevent resistance.
Since her foray into biology at the American Museum of Natural History almost a decade ago, Vassel has maintained her passion for science outreach. During her time at MIT, she has served as a math tutor for middle schoolers in the Cambridge public school system. She also volunteered as a science and math mentor for high school students, as part of a dual athletic and academic program founded by MIT.
As Vassel wraps up her final year of graduate studies, she is torn between completing an academic postdoc and indulging her early interest in science education policy.
“Growing up in New York City, it was not lost on me that — despite the city’s wonderful diversity — people from historically underserved groups were still missing from many science-related positions,” Vassel says. “It got me thinking about the dire need for policymakers to improve curricula to make science more inclusive of all life experiences. There’s this idea that science is apolitical when it’s really not, and that mindset can have detrimental effects on equity and diversity in science.”
“Returning to the subway map analogy, this labeling technique is similar to not only being inside the subway, but also giving everyone in Downtown Boston a red shirt,” Li says. “After 12 hours, we can look at the rest of the city. If we see a lot of red shirts in Allston, we would know that this particular route is really popular.”
