Research Area: Biochemistry, Biophysics, and Structural Biology

New player in cellular signaling

Researchers have identified a key nutrient sensor in the mTOR pathway that links nutrient availability to cell growth.

Nicole Giese Rura | Whitehead Institute
November 9, 2017

To survive and grow, a cell must properly assess the resources available and couple that with its growth and metabolism — a misstep in that calculus can potentially cause cell death or dysfunction. At the crux of these decisions is the mTOR pathway, a cellular pathway connecting nutrition, metabolism, and disease.

The mTOR pathway incorporates input from multiple factors, such as oxygen levels, nutrient availability, growth factors, and insulin levels to promote or restrict cellular growth and metabolism. But when the pathway runs amok, it can be associated with numerous diseases, including cancer, diabetes, and Alzheimer’s disease. Understanding the various sensors that feed into the mTOR pathway could lead to novel therapies for these diseases and even aging, as dialing down the mTOR pathway is linked to longer lifespans in mice and other organisms.

Although the essential amino acid methionine is one of the key nutrients whose levels cells must carefully sense, researchers did not know how it fed into the mTOR pathway — or if it did at all. Now, Whitehead Institute Member David Sabatini and members of his laboratory have identified a protein, SAMTOR, as a sensor in the mTOR pathway for the methionine derivative SAM (S-adenosyl methionine). Their findings are described in the current issue of the journal Science.

Methionine is essential for protein synthesis, and a metabolite produced from it, SAM, is involved in several critical cellular functions to sustain growth, including DNA methylation, ribosome biogenesis, and phospholipid metabolism. Interestingly, methionine restriction at the organismal level has been linked to increased insulin tolerance and lifespan, similar to the antiaging effects associated with inhibition of mTOR pathway activity. But the connection between mTOR, methionine, and aging remains elusive.

“There are a lot of similarities between the phenotypes of methionine restriction and mTOR inhibition,” says Sabatini, who is also a Howard Hughes Medical Institute investigator and a professor of biology at MIT. “The existence of this protein SAMTOR provides some tantalizing data suggesting that those phenotypes may be mechanistically connected.”

Sabatini identified mTOR as a graduate student and has since elucidated numerous aspects of its namesake pathway. He and his lab recently pinpointed the molecular sensors in the mTOR pathway for two key amino acids: leucine and arginine. In the current line of research, co-first authors of the Science paper Xin Gu and Jose Orozco, both graduate students Sabatini’s lab, identified a previously uncharacterized protein that seemed to interact with components of the mTOR pathway. After further investigation, they determined that the protein binds to SAM and indirectly gauges the pool of available methionine, making this protein — SAMTOR — a specific and unique nutrient sensor that informs the mTOR pathway.

“People have been trying to figure out how methionine was sensed in cells for a really long time,” Orozco says. “I think that this is the first time in mammalian cells a mechanism has been found to describe the way methionine can regulate a major signaling pathway like mTOR.”

The current research indicates that SAMTOR plays a crucial role in methionine sensing. Methionine metabolism is vital for many cellular functions, and the Sabatini lab will further investigate the potential links between SAMTOR and the extended lifespan and increased insulin sensitivity effects that are associated with low methionine levels.

“It is very interesting to consider mechanistically how methionine restriction might be associated in multiple organisms with beneficial effects, and identification of this protein provides us a potential molecular handle to further investigate this question,” Gu says. “The nutrient-sensing pathway upstream of mTOR is a very elegant system in terms of responding to the availability of certain nutrients with specific mechanisms to regulate cell growth. The currently known sensors raise some interesting questions about why cells evolved sensing mechanisms to these specific nutrients and how cells treat these nutrients differently.”

This work was supported by the National Institutes of Health, the Department of Defense, the National Science Foundation, and the Paul Gray UROP Fund.

A new workflow for natural product characterization comes ashore with red algae
October 30, 2017

CAMBRIDGE, Mass. – A few years ago while paddling off the coast near La Jolla, California, avid surfer Roland Kersten noticed a piece of red algae (Laurenica pacifica) bobbing alongside his surfboard. Kersten, whose background is in natural product chemistry, was intrigued.

Natural products—chemicals from living organisms such as plants and algae—represent a rich source of potential therapeutics. A majority of anti-cancer drugs are natural product-based or inspired. One such well-known natural product—the potent anti-cancer drug Taxol—was identified in the bark of a yew tree.

Marine algae, like the red algae Kersten found, are often rich in compounds called sesquiterpenes, some of which have been shown to have potential medicinal attributes. Since the 1970s, scientists identified many sesquiterpenes produced by Laurencia species with anti-cancer properties. The identification techniques usually required about tens of milligrams of purified compounds, which were obtained from more than a kilogram of algae. Because Laurencia and the reef ecosystems in which it thrives are protected, and such large-scale harvesting for scientific or medicinal purposes is no longer tenable, Kersten had to devise a different approach to analyze its sesquiterpenes.

Kersten received a collection permit to clamber over the rocky shore at deep low tide to collect a hand-sized sample of the red algae. Now a postdoctoral fellow in the lab of Whitehead Member and Massachusetts Institute of Technology assistant professor of biology Jing-Ke Weng, Kersten’s first task was to search the RNA sequences of all genes expressed in his red algae sample to find those whose product seemed likely to be enzymes that make sesquiterpenes.  In order to determine the product generated by these enzymes, he engineered them in yeast and isolated its sesquiterpene products.

In order to define the first step in the biogenesis of sesquiterpenes in red algae, Kersten wanted to see the precise 3-D structure of the isolated sesquiterpene. But the small handful of algae he had obtained produced only a fraction of the amount required for x-ray crystallography, the established method for determining a compound’s absolute structure. So Kersten tried a method recently developed by collaborator Makoto Fujita at the University of Tokyo that requires only a few nanograms of material: soaking extracted compounds into a special crystalline sponge, which supports the sample’s molecular shape while it is bombarded with x-rays to accurately determine the 3-D conformation of a molecule. A new combination of the crystalline sponge method and nuclear magnetic resonance spectroscopy by the Fujita group revealed the structure of prespatane.

With the compound’s structure in hand, Kersten is closer to understanding how Laurenciabiosynthesizes its sesquiterpenes and how to engineer yeast to produce the same molecules for medicinal research at scale—without touching the red algae flourishing on protected reefs. And the novel workflow—spanning genomics, metabolomics, synthetic biology, and x-ray crystallography with crystalline sponges—established by Weng, Kersten, and their collaborators may expedite the identification of other promising compounds produced by organisms from both land and sea.

Other contributors to this work include Shoukou Lee of Tokyo University, Daishi Fujita of Tokyo University and Whitehead Institute, Tomáš Pluskal of Whitehead Institute.  The team also collaborated with researchers from Scripps Institution of Oceanography and Salk Institute of Biological Sciences.

This work was supported by Howard Hughes Medical Institute, the Simons Foundation, the Helen Hay Whitney Foundation, the Pew Scholars Program in the Biomedical Sciences, the Searle Scholars Program, and the Japan Science and Technology Agency.

 Written by Nicole Giese Rura
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Jing-Ke Weng’s primary affiliation is with Whitehead Institute for Biomedical Research, where his laboratory is located and all his research is conducted. He is also an assistant professor of biology at Massachusetts Institute of Technology.
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Full Citation:
“A Red Algal Bourbonane Sesquiterpene Synthase Defined by Microgram-scale NMR-coupled Crystalline Sponge XRD Analysis”
Journal of the American Chemical Society, online October 30, 2017.
Roland D. Kersten (1,6), Shoukou Lee (2,6) , Daishi Fujita (1,2) , Tomáš Pluskal (1) , Susan Kram (3), Jennifer E. Smith (3) , Takahiro Iwai (2) , Joseph P. Noel (4) , Makoto Fujita (2), Jing-Ke Weng (1,5).
1. Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA, United States
2. Graduate School of Engineering, The University of Tokyo, JST-ACCEL, Tokyo, Japan
3. Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, United States
4. Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, CA, United States
5. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
6. These authors contributed equally
School of Science welcomes new faculty members

This fall brings 14 new professors in the departments of Biology, Chemistry, Mathematics, and Physics.

School of Science
October 10, 2017

This fall, the MIT School of Science has welcomed 14 new professors in the departments of Biology, Chemistry, Mathematics, and Physics.

Ian J. M. Crossfield focuses on the atmospheric characterization of exoplanets through all possible methods — transits, eclipses, phase curves, and direct imaging — from the ground and from space, with an additional interest in the discovery of new exoplanets, especially those whose atmospheres that can be studied in more detail. He joins the MIT Department of Physics as an assistant professor.

Joey Davis, an assistant professor in the Department of Biology, studies the molecular mechanisms underpinning autophagy using biochemical, biophysical, and structural biology techniques such as mass spectrometry and cryo-electron microscopy. This pathway is responsible for protein and organelle degradation and has been linked to a variety of aging associated disorders including neurodegeneration and cancer.

Daniel Harlow works on black holes and cosmology, viewed through the lens of quantum gravity and quantum field theory. He has joined the Department of Physics as assistant professor.

Philip Harris, a new assistant professor in the Department of Physics, searches for dark matter, seeking a deeper understanding of the petabytes of data collected at the Large Hadron Collider. Much of his research exploits new techniques to resolve the structure of quark and gluon decays, known as jet substructure.

Or Hen studies quantum chromodynamics effects in the nuclear medium, and the interplay between partonic and nucleonic degrees of freedom in nuclei, conducting experiments at the Thomas Jefferson and Fermi National Accelerator Laboratories, as well as other accelerators around the world. He has joined the faculty as an assistant professor in the Department of Physics and the Laboratory of Nuclear Science.

Laura Kiessling investigates how carbohydrates are assembled, recognized, and function in living cells, which is crucial to understanding key biological processes such as bacterial cell wall biogenesis, bacteria chemotaxis, enzyme catalysis and inhibition, immunity, and stem cell propagation and differentiation. She is the new Novartis Professor of Chemistry.

Rebecca Lamason investigates how intracellular bacterial pathogens hijack host cell processes to promote infection. In particular, she studies how Rickettsia parkeri and Listeria monocytogenes move through tissues via a process called cell-to-cell spread. She has joined the Department of Biology as an assistant professor.

Sebastian Lourido studies the molecular events that enable parasites in the phylum Apicomplexa to remain widespread and deadly infectious agents. Lourido uses Toxoplasma gondii to model processes conserved throughout the phylum, in order to expand our understanding of eukaryotic diversity and identify specific features that can be targeted to treat parasite infections. He has been welcomed into the Department of Biology as an assistant professor.

Ronald T. Raines, who has joined the faculty as the Firmenich Professor of Chemistry, uses techniques that range from synthetic chemistry to cell biology to illuminate in atomic detail both the chemical basis and the biological purpose for protein structure and protein function. He seeks insights into the relationship between amino-acid sequence and protein function (or dysfunction), as well as to the creation of novel proteins with desirable properties.

Giulia Saccà is an algebraic geometer with a focus on hyperkähler and Calabi-Yau manifolds, K3 surfaces, moduli spaces of sheaves, families of abelian varieties and their degenerations, and symplectic resolutions. She is now an assistant professor in the Department of Mathematics.

Stefani Spranger studies the interactions between cancer and the immune system, with the goal of improving existing immunotherapies or developing novel therapeutic approaches. Spranger seeks to understand how CD8 T cells, otherwise known as killer T cells, are excluded from the tumor microenvironment, with a focus on lung and pancreatic cancers. She has joined the Department of Biology as an assistant professor.

Daniel Suess works at the intersection of inorganic and biological chemistry, studying redox reactions that underpin global biogeochemical cycles, metabolism, and energy conversion. He develops chemical strategies for attaining precise, molecular-level control over the structures of complex active sites. In doing so, his research yields detailed mechanistic insight and enables the preparation of catalysts with improved function. Suess is an assistant professor in the Department of Chemistry.

Wei Zhang is a number theorist who works in arithmetic geometry, with special interest in fundamental objects such as L-functions, which appear in the Riemann hypothesis and its generalizations, and are central to the Langlands program. Zhang has joined the Department of Mathematics as a full professor.

Yufei Zhao, who has joined the Department of Mathematics as an assistant professor, works in combinatorics and graph theory, and is especially interested in problems with extremal, probabilistic, and additive flavors.

Department of Biology hosts its first Science Slam

Eight biology trainees had just three minutes to explain their research and earn favor with the judges and audience in new yearly event.

Raleigh McElvery | Department of Biology
October 5, 2017

Nearly 300 spectators crowded into a lecture hall at the Ray and Maria Stata Center on a recent Tuesday to witness the first annual Science Slam, hosted by MIT’s Department of Biology.

A science slam features a series of short presentations where researchers explain their work in a compelling manner and — as the name suggests — make an impact. The presentations aren’t just talks, they’re performances geared towards a science-literate but non-specialized public audience. In this case, competitors were each given one slide and three minutes to tell their scientific tales and earn votes from audience members and judges.

The jury included Ellen Clegg, editorial page editor of The Boston Globe and co-author of two award-winning books, “ChemoBrain” and “The Alzheimer’s Solution;” Emilie Marcus, CEO of Cell Press and editor-in-chief of the flagship journal, Cell; and Ari Daniel, an independent science reporter who produces digital videos for PBS NOVA and co-produces the Boston branch of Story Collider.

Among the competitors were five graduate students and three postdocs who hailed from labs scattered throughout Building 68, the Whitehead Institute, the Broad Institute, the Koch Institute for Integrative Cancer Research, and the Picower Institute for Learning and Memory. The storytellers were:

  • Sahin Naqvi, from David Page’s lab, who spoke about the evolution of genetic sex differences in mammals, as well as how these differences impact the likelihood of developing certain diseases based on gender;
  • Sudha Kumari, from Darrell Irvine’s lab, who spoke about her work investigating immune cell interactions — specifically how T cells communicate using physical contact;
  • Deniz Atabay, from Peter Reddien’s lab, who spoke about the ways cells in flatworms self-organize during regeneration to re-form organs, tissues, and even neural circuits;
  • Emma Kowal, from Christopher Burge’s lab, who spoke about her goals to demystify the ways in which certain noncoding regions of genetic sequence, known as introns, contribute to protein production;
  • Xin Tang, from Rudolf Jaenisch’s lab, who spoke about a technique to illuminate the seemingly invisible changes in brain cells that trigger disease, using a glowing enzyme from a firefly;
  • Nicole Aponte, from Troy Littleton’s lab, who spoke about her ability to manipulate brain cell activity in the fruit fly, and study how defects in neuronal connections contribute to developmental disorders;
  • Karthik Shekhar, from Aviv Regev’s lab, who spoke about his efforts to identify and manipulate different types of brain cells, understanding how they assemble into complex networks to facilitate learning, memory, and — in some cases — disease; and
  • Monika Avello, from Alan Grossman’s lab, who spoke about “bacterial sexology,” that is, how and why these organisms choose to block unwanted sexual advances from fellow bacteria.

Vivian Siegel, who oversees the department’s communications efforts, moderated the event. Siegel and the Building 68 communications team joined forces with three members of the Building 68 MIT Postdoctoral Association — Ana Fiszbein, Isabel Nocedal, and Peter Sudmant — to publicize the event and to host two pre-slam workshops, as well as one-on-one training sessions with individual participants.

“Participating in a Science Slam seemed like a great way for our trainees to learn how to communicate to a nonspecialized audience, which is something they will need to be able to do throughout their careers,” Siegel said. “We really wanted to develop a camaraderie among the participants, and bring trainees together from across the department to help each other tell compelling stories about their science.”

Kowal — whose talk was titled “Gone but Not Forgotten: How Do Introns Enhance Gene Expression?”  — ultimately took home both the audience and jury cash prizes. Kowal completed her undergraduate degree in chemical and physical biology at Harvard before coming to MIT for graduate school. Her dream is to write science fiction, so she decided she’d better study science so she’d know what to write about.

“I really enjoyed seeing people get stoked about introns, and the fact that they enhance gene expression,” she said. “It’s a great way to get comfortable explaining your project in a compelling way to a broad audience. Since you’ll probably be telling people about your work for a while, I think it’s a very good use of time to practice doing that.”

Biologists identify possible new strategy for halting brain tumors

Cutting off a process that cancerous cells rely on can force them to stop growing.

Anne Trafton | MIT News Office
September 28, 2017

MIT biologists have discovered a fundamental mechanism that helps brain tumors called glioblastomas grow aggressively. After blocking this mechanism in mice, the researchers were able to halt tumor growth.

The researchers also identified a genetic marker that could be used to predict which patients would most likely benefit from this type of treatment. Glioblastoma is usually treated with radiation and the chemotherapy drug temozolamide, which may extend patients’ lifespans but in most cases do not offer a cure.

“There are very few specific or targeted inhibitors that are used in the treatment of brain cancer. There’s really a dire need for new therapies and new ideas,” says Michael Hemann, an associate professor of biology at MIT, a member of MIT’s Koch Institute for Integrative Cancer Research, and a senior author of the study.

Drugs that block a key protein involved in the newly discovered process already exist, and at least one is in clinical trials to treat cancer. However, most of these inhibitors do not cross the blood-brain barrier, which separates the brain from circulating blood and prevents large molecules from entering the brain. The MIT team hopes to develop drugs that can cross this barrier, possibly by packaging them into nanoparticles.

The study, which appears in Cancer Cell on Sept. 28, is a collaboration between the labs of Hemann; Jacqueline Lees, associate director of the Koch Institute and the Virginia and D.K. Ludwig Professor for Cancer Research; and Phillip Sharp, an MIT Institute Professor and member of the Koch Institute. The paper’s lead authors are former MIT postdoc Christian Braun, recent PhD recipient Monica Stanciu, and research scientist Paul Boutz.

Too much splicing

Several years ago, Stanciu and Braun came up with the idea to use a type of screen known as shRNA to seek genes involved in glioblastoma. This test involves using short strands of RNA to block the expression of specific genes. Using this approach, researchers can turn off thousands of different genes, one per tumor cell, and then measure the effects on cell survival.

One of the top hits from this screen was the gene for a protein called PRMT5. When this gene was turned off, tumor cells stopped growing. Previous studies had linked high levels of PRMT5 to cancer, but the protein is an enzyme that can act on hundreds of other proteins, so scientists weren’t sure exactly how it was stimulating cancer cell growth.

Further experiments in which the researchers analyzed other genes affected when PRMT5 was inhibited led them to hypothesize that PRMT5 was using a special type of gene splicing to stimulate tumor growth. Gene splicing is required to snip out portions of messenger RNA known as introns, that are not needed after the gene is copied into mRNA.

In 2015, Boutz and others in Sharp’s lab discovered that about 10 to 15 percent of human mRNA strands still have one to three “detained introns,” even though they are otherwise mature. Because of those introns, these mRNA molecules can’t leave the nucleus.

“What we think is that these strands are basically an mRNA reservoir. You have these unproductive isoforms sitting in the nucleus, and the only thing that keeps them from being translated is that one intron,” says Braun, who is now a physician-scientist at Ludwig Maximilian University of Munich.

In the new study, the researchers discovered that PRMT5 plays a key role in regulating this type of splicing. They speculate that neural stem cells utilize high levels of PRMT5 to guarantee efficient splicing and therefore expression of proliferation genes. “As the cells move toward their mature state, PRMT5 levels drop, detained intron levels rise, and those messenger RNAs associated with proliferation get stuck in the nucleus,” Lees says.

When brain cells become cancerous, PRMT5 levels are typically boosted and the splicing of proliferation-associated mRNA is improved, ultimately helping the cells to grow uncontrollably.

Predicting success

When the researchers blocked PRMT5 in tumor cells, they found that the cells stopped dividing and entered a dormant, nondividing state. PRMT5 inhibitors also halted growth of glioblastoma tumors implanted under the skin of mice, but they did not work as well in tumors located in the brain, because of the difficulties in crossing the blood-brain barrier.

Unlike many existing cancer treatments, the PRMT5 inhibitors did not appear to cause major side effects. The researchers believe this may be because mature cells are not as dependent as cancer cells on PRMT5 function.

The findings shed light on why researchers have previously found PRMT5 to be a promising potential target for cancer treatment, says Omar Abdel-Wahab, an assistant member in the Human Oncology and Pathogenesis Program at Memorial Sloan Kettering Cancer Center, who was not involved in the study.

“PRMT5 has a lot of roles, and until now, it has not been clear what is the pathway that is really important for its contributions to cancer,” says Abdel-Wahab. “What they have found is that one of the key contributions is in this RNA splicing mechanism, and furthermore, when RNA splicing is disrupted, that key pathway is disabled.”

The researchers also discovered a biomarker that could help identify patients who would be most likely to benefit from a PRMT5 inhibitor. This marker is a ratio of two proteins that act as co-factors for PRMT5’s splicing activity, and reveals whether PRMT5 in those tumor cells is involved in splicing or some other cell function.

“This becomes really important when you think about clinical trials, because if 50 percent or 25 percent of tumors are going to have some response and the others are not, you may not have a way to target it toward those patients that may have a particular benefit. The overall success of the trial may be damaged by lack of understanding of who’s going to respond,” Hemann says.

The MIT team is now looking into the potential role of PRMT5 in other types of cancer, including lung tumors. They also hope to identify other genes and proteins involved in the splicing process they discovered, which could also make good drug targets.

Spearheaded by students and postdocs from several different labs, this project offers a prime example of the spirit of collaboration and “scientific entrepreneurship” found at MIT and the Koch Institute, the researchers say.

“I think it really is a classic example of how MIT is a sort of bottom-up place,” Lees says. “Students and postdocs get excited about different ideas, and they sit in on each other’s seminars and hear interesting things and pull them together. It really is an amazing example of the creativity that young people at MIT have. They’re fearless.”

The research was funded by the Ludwig Center for Molecular Oncology at MIT, the Koch Institute Frontier Research Program through the Kathy and Curt Marble Cancer Research Fund, the National Institutes of Health, and the Koch Institute Support (core) Grant from the National Cancer Institute.

Three MIT biologists receive NIH Outstanding Investigator Awards

Graham Walker, Michael Yaffe, and Robert Weinberg earn support from the National Institutes of Health to further their research endeavors.

Raleigh McElvery | Department of Biology
September 19, 2017

This fall, two faculty members from the MIT Department of Biology received R35 Outstanding Investigator Awards sponsored by the National Institute of Environmental Health Sciences (NIEHS), while a third garnered the same distinction from the National Cancer Institute (NCI). These awards provide long-term support to experienced investigators with outstanding records of research productivity as they undertake lengthy projects with unusual potential.

Graham Walker, the American Cancer Society Professor in the Department of Biology at MIT, a member of the Center for Environmental Health Sciences, and affiliate member of the Koch Institute for Integrative Cancer Research, is one of two biology faculty to earn the R35 Outstanding Investigator Award from the NIEHS.

This award is supported by the NIEHS through the Revolutionizing Innovative, Visionary Environmental health Research (RIVER) program. The program recognizes outstanding investigators in the field of environmental health, potentially offering up to $750,000 per year over the next eight years.

The awardees include both mid-career and senior researchers, whose work spans many aspects environmental health science — including technology development, mechanistic, clinical, and epidemiological research. A total of eight investigators received the NIEHS RIVER R35 this year.

“The RIVER program is designed to fund people, not projects,” said David Balshaw, chief of the NIEHS Exposure, Response, and Technology Branch who leads the NIEHS team overseeing this initiative. “It gives outstanding environmental health scientists stable funding, time, and, importantly, flexibility to pursue creative scientific ideas, rather than constantly writing grants to support their research programs.”

Walker will use his award to continue investigating the fundamental mechanisms of mutagenesis and DNA repair, with a special emphasis on the Rev1/3/7-dependent pathway of mutagenic translation synthesis found in eukaryotes, including humans. He and his colleagues recently published evidence suggesting that inhibiting this pathway could potentially improve chemotherapy.

Michael Yaffe, the David H. Koch Professor of Science at MIT, a member of the Koch Institute and the Center for Environmental Health Sciences, and attending surgeon at the Beth Israel Deaconess Medical Center, also received a NIEHS RIVER R35 award.

Yaffe’s work concerns how cells respond to injury, including damage to DNA and RNA molecules arising because of the environment and in response to drugs used to treat cancer. He is also interested in the relationship between inflammation, blood clotting, and cancer. He employs multidisciplinary approaches harnessing techniques from biochemistry, structural and cell biology, computer science, and systems biology/engineering.

Yaffe will use his funds to further a project investigating the roles of protein kinases in coordinating cellular responses to damage to both DNA and RNA molecules.

Robert Weinberg, founding member of the Whitehead Institute, professor of biology at MIT, an affiliate member of the Koch Institute, and director of the MIT Ludwig Center for Molecular Oncology, has received his R35 Outstanding Investigator Award from the NCI.

The award provides up to $600,000 per year over seven years to accomplished cancer researchers, nominated by their institutions, who have served as principal investigators on an NCI grant for the last five years. A total of 18 investigators received the NCI Outstanding Investigator Award this year.

“The NCI Outstanding Investigator Award addresses a problem that many cancer researchers experience: finding a balance between focusing on their science while ensuring that they will have funds to continue their research in the future,” said Dinah Singer, director of NCI’s Division of Cancer Biology. “With seven years of uninterrupted funding, NCI is providing investigators the opportunity to fully develop exceptional and ambitious cancer research programs.”

Weinberg is a pioneer in cancer research, best known for his role in discovering the first human oncogene — a gene that, when activated, can spur tumor growth. His lab is also credited with isolating the first known tumor suppressor gene.

He will use his funds to delve into the mechanisms of metastasis — the process that allows cancer cells to spread. He aims to learn more about how these cells disseminate from primary tumors, as well as how they become established in distant tissues after they metastasize.

New faculty welcomed to Department of Biology

Assistant professors Joey Davis and Rebecca Lamason will spearhead research initiatives into fundamental cellular processes.

Raleigh McElvery | Department of Biology
September 11, 2017

MIT’s Department of Biology is welcoming two new assistant professors, Joey Davis and Rebecca Lamason, this September. The duo will augment the department’s efforts in basic research, probing fundamental facets of cellular processes like molecular degradation and bacterial infection.

“I am thrilled that Becky and Joey have joined our department,” says Alan Grossman, department head. “They bring new research areas and approaches that fit well with our overarching goals to help solve fundamental biological problems. I anticipate that their expertise and interests will enable collaborations within MIT and beyond.”

The arrival of Davis and Lamason brings the number of recent biology faculty additions to five since January.

Joey Davis

Joey Davis investigates how cells maintain a delicate internal balance of assembling and dismantling their own machinery, particularly macromolecules. A cell’s ability to keep the precarious balance of this process in check often diminishes with age, and when it goes awry, disease can ensue.

Born in Durango, Colorado, but raised in Long Beach, California, Davis became interested in how things were built by emulating his construction worker father. Assembling bicycles and other objects spurred Davis’ curiosity about the nuts and bolts of the natural world and he soon realized that, unlike bikes, biological systems were not so easily parsed.

Davis went on to earn dual bachelor’s degrees in biological engineering and computer science from the University of California at Berkeley. He arrived at MIT as a graduate student shortly thereafter, jointly advised by professors Robert Sauer and Tania Baker, both of whom are based in Building 68, where Davis will now run his own lab. He also served as a teaching assistant for 7.51 (Principles of Biochemical Analysis), and as an advisor to MIT’s team for the International Genetically Engineered Machines (iGEM) competition.

Davis became enthralled by molecular disassembly, particularly in bacteria. After a brief foray into the biotechnology sector, he returned to his California roots to pursue his postdoctoral training at the Scripps Research Institute in La Jolla. He brought with him his MIT-inspired fervor for large cellular machinery, and in doing so encountered his macromolecule of choice: the ribosome. Sometimes referred to by researchers as the “construction workers” of cells, ribosomes play a key role in building molecules from genetic blueprints. After three years, he was awarded a K99/R00 Pathway to Independence Award from the National Institute of Aging, which included an affiliation at the Sanford Burnham Prebys Medical Discovery Institute. The award will also help fund his first several years of research at MIT.

In his own lab, Davis seeks to determine how cells assemble and destroy ribosomes and other macromolecules, as well as how they remove harmful protein aggregates and dysfunctional organelles. These functions are often compromised due to age, genetic mutations, and environmental stresses, leading to diseases like cancer, diabetes, and neurodegenerative disorders. Davis says he is excited to further examine these processes at MIT.

“The questions I’m asking about how the degradation system is constructed and how it targets substrates are similar to those I pursued in graduate school — but the answers will likely be completely different,” Davis says. “The members of the MIT research community truly want to know how the natural world works, and that mindset draws me in today as much as it did 13 years ago.”

Davis has been hard at work developing a series of new research techniques, some involving cryo-electron microscopy, a method to image large macromolecules at high resolution. His discoveries could ultimately assist pharmaceutical development — improving antibiotics and anti-cancer therapeutics — and perhaps enabling scientists to one day engineer their own bigger and better molecules.

Rebecca Lamason

Rebecca Lamason investigates what happens when cellular functions are hijacked by unwanted interlopers — namely, the bacteria that cause diseases such as spotted fever and meningitis. Her interdisciplinary work spans multiple fields, including immunology, genetics, biochemistry, cell biology, and microbiology.

Growing up in a family that was interdisciplinary in its own right, composed of both artists and mechanics, Lamason has always sought to examine fundamental questions from multiple perspectives.

After earning a bachelor’s degree in molecular biology from Millersville University in Pennsylvania, she went on to graduate school at the Johns Hopkins University School of Medicine, where she immersed herself in the field of immunology. There she demonstrated how a molecule called CARD11 regulates immune cell activation, a discovery with potential applications for cancer therapeutics. She also served as a teaching assistant for the school’s graduate immunology course and co-founded the Immunology Student Journal Club.

It wasn’t until her postdoctoral training at the University of California at Berkeley, however, that Lamason found her model systems: two species of bacteria called Rickettsia parkeri and Listeria monocytogenes.

The two pathogens lay siege to cells in much the same way, entering and leveraging preexisting internal structures to build tails for rapid migration to neighboring cells. Lamason hypothesized that to do so, the intruders must also take over the complex communication systems between cells. Common scientific consensus held for years that Rickettsia, Listeria, and several other species of bacteria spread in a similar manner — using their tails to propel themselves and ram into the host’s cell wall to gain access to neighboring cells. Lamason, however, demonstrated this isn’t always the case and that Rickettsia tend to lose their tails and must then rely on the host cell’s internal machinery instead to invade neighboring cells.

Lamason was drawn to MIT by the diverse array of research efforts that are unified by a collaborative desire to explore the mechanistic details of cellular systems. Like Davis, she received a K99/R00 Pathway to Independence Award in 2015 — in her case from the National Institute of General Medical Sciences. Her lab will continue to investigate the interplay between invasive bacteria and their hosts, aiming to clarify how cell-to-cell spread varies between species. She plans to leverage advanced imaging platforms with tools from cell biology, microbiology, genetics, and biophysics to gain a deeper understanding of how these pathogens manipulate their hosts.

“My goal is to understand this virulence mechanism in order to prevent disease, and to use pathogens as tools to better understand host cell biology,” Lamason says. “This type of study lends itself naturally to interdisciplinary work. I love the challenge of learning new things and using multiple approaches to clarify important biological questions.”

Department of Biology welcomes three new faculty members

Recent additions bring diverse expertise and cultural perspectives to research community.

Raleigh McElvery | Department of Biology
July 25, 2017

On July 1, MIT Department of Biology welcomed three new faculty members. Since they were all born outside the continental U.S., these newcomers add to the diversity of cultural experiences and contribute to the global face of science at MIT and its affiliated institutions around Kendall Square. The triad also enhances the department’s diverse array of research initiatives. Their interests are as far-reaching as their roots, and range from investigating genetic diseases and cancer immunotherapy to exploiting parasite vulnerabilities.

“When creative individuals with distinct perspectives and approaches come together in an innovative environment like MIT, the possibilities for scientific collaboration and accomplishment are exceptional,” says Alan Grossman, head of the department. “I couldn’t be more pleased to welcome three such outstanding and accomplished individuals into our research community.”

Eliezer Calo

Eliezer Calo is no stranger to MIT. Although he grew up on a farm more than a thousand miles away in the mountains of Carolina, Puerto Rico, Calo first set foot in MIT’s Building 68 11 years ago — and hasn’t wavered in his decision to become a biologist since. In 2006, as part of the MIT Summer Research Program (MSRP), Calo spent 10 weeks studying under Professor Stephen Bell, examining DNA replication. At the time, Calo was a chemistry major at the University of Puerto Rico, but returned post-graduation to MIT’s Department of Biology, earning his PhD while serving as both a teaching assistant for MIT’s course 7.01 (Introduction to Biology) and MSRP program assistant.

“MIT is very unique,” he says. “I’ve done research at multiple institutions, and yet nothing quite compares. Here, the impossible is made possible.”

After completing his postdoctoral training at Stanford University, Calo returned to Cambridge, Massachusetts, this past January as an assistant professor and extramural member at the Koch Institute to head his own lab — exploring the ways in which errors in cellular organelles called ribosomes can lead to disease.

Ribosomes are vital to the translation of genetic code into the molecules integral to life, but are far less often acknowledged for their role in embryonic development. Calo suggests that when ribosomes are not constructed correctly, they are unable to carry out their cellular duties, hindering cell growth and causing developmental disorders. Calo is interested in one condition specifically: Treacher Collins syndrome, which stems from a mutation in a single gene that impedes proper ribosomal assembly. He will soon transfer his experiments from cell cultures to a new model system — zebrafish — in order to further unravel the relationship between ribosome structure and disease.

“The research I do now is purely based on my interest in understanding how cells work,” Calo says. “Specifically, how the mechanisms controlling growth and proliferation operate. These are essential processes that led to the emergence of multicellular organisms, and thus to our own existence.”

Stefani Spranger

One building over in MIT’s Koch Institute, newly-appointed Assistant Professor Stefani Spranger will work to harness the body’s own defense force to pinpoint and eradicate cancer. Spranger carried her passion for immunotherapy across seas from Munich, Germany. As the daughter of two engineers, Spranger was raised on science. “My parents fostered my curiosity,” she says, “which led to my initial motivation to go into science: to figure out how things work.”

While earning her bachelor’s and master’s degrees from the Ludwig-Maximilians University of Munich, Spranger discussed publications focusing on two clinical trials that used engineered immune cells to combat malignant melanoma. These publications ignited Spranger’s enthusiasm for immune-based therapies, which in turn spurred her doctoral and postdoctoral training at the Helmholtz-Zentrum Munich in the Institute for Molecular Immunology and the University of Chicago, respectively.

While Spranger’s education helped hone her immunology research skills, she is excited to experience a more varied academic environment encompassing a range of disciplines. “I was drawn to MIT because of its diverse faculty and the breadth of research interests,” she says.

Spranger’s lab will employ tumor models in mice to determine how cancer and immune cells interact. In particular, she aims to discern the many factors related to the cells, tissues, and environment that could affect the immune system’s anti-tumor response. Ultimately, Spranger hopes to contribute to new treatments that trigger the body’s defense to thwart cancer.

Sebastian Lourido

Trained as both an artist and a scientist, Sebastian Lourido works to counter an entirely different kind of invader spreading biological mayhem: parasites. Originally from Colombia, he was recently named assistant professor of biology, joining the cohort of 15 faculty members at the Whitehead Institute for Biomedical Research — one of just 28 individuals to ever receive this appointment. The title may be new, but this is familiar turf for Lourido. He became a Whitehead Fellow in 2012, after receiving his PhD in microbiology from Washington University in St. Louis and a bachelor’s in studio art and cell and molecular biology from Tulane University. A pioneer in more ways than one, Lourido formed his own lab as a fellow rather than following a more conventional postdoc path.

Lourido spent much of his childhood exploring his mother’s genetics lab, where he analyzed practically anything he could fit under a microscope. “That experience solidified my excitement for the invisible mechanisms that make up the living world,” he says. “I can’t remember a time when I didn’t know that genetic information was carried in our cells in the form of DNA, and passed from one generation to the next.”

Constantly seeking ways to merge his artistic endeavors with scientific ones, Lourido leverages his creativity to glean insight into the systems and structures that constitute life.  He probes a group of microscopic invaders known as Apicomplexan parasites, revealing their weaknesses in order to devise potential treatments. Lourido’s team was the first to perform a genome-wide functional analysis of an apicomplexan — gaining deeper understanding of the genes and molecules key for the invasion process. In 2013, Lourido received the National Institutes of Health (NIH) Director’s Early Independence Award, and with it a five-year grant to investigate motility in one kind of parasite, Toxoplasma gondii. This same interloper is also the subject of Lourido’s two-year NIH-funded project, for which he is the principal investigator.

Lourido has found the MIT community both welcoming and inclusive. Even as he was interviewing for his new position, he was struck by the collaborative, collegial, and nurturing environment.

“This level of engagement permeates the other elements of our community — students, postdocs, and staff scientists — who drive the exciting research happening every day at MIT,” he says. “There are many forces that shape the diversity of our campus, and we need to be vigilant and work hard to continue to encourage and support scientists from different backgrounds, experiences, and cultures.”

Microbe generates extraordinarily diverse array of peptides

In marine bacteria, evolution of new specialized molecules follows a previously unknown path.

David L. Chandler | MIT News Office
June 22, 2017

It’s one of the tiniest organisms on Earth, but also one of the most abundant. And now, the microscopic marine bacteria called Prochlorococcus can add one more superlative to its list of attributes: It evolves new kinds of metabolites called lanthipeptides, more abundantly and rapidly than any other known organism.

While most bacteria contain genes to pump out one or two versions of this peptide, Prochlorococcus varieties can each produce more than two dozen different peptides (molecules that are similar to proteins, but smaller). And though all of Earth’s Prochlorococcus varieties belong to just a single species, some of their localized varieties in different regions of the world’s oceans each produce a unique collection of thousands of these peptides, unlike those generated by terrestrial bacteria.

The startling findings, published this week in the journal Proceedings of the National Academy of Science, were discovered by former MIT graduate student Andres Cubillos-Ruiz, Institute Professor Sallie “Penny” Chisholm, University of Illinois chemistry professor Wilfred van der Donk, and two others.

“This is incredibly significant work,” says Eric Schmidt, professor of medicinal chemistry at the University of Utah, who was not involved in the research. “The authors show how nature has evolved methods to create chemical diversity. What really sets it apart is that it examines how this evolution takes place in nature, instead of in the lab. They examine a huge habitat, the open ocean. This is amazing,” he says.

“No one had seen the true extent of the diversity in these molecules” until this new study, Cubillos-Ruiz says. The first hints of this unexpected diversity surfaced in 2010, when Bo Li and Daniel Sher, members of van der Donk’s and Chisholm’s labs respectively, found that one variety of Prochlorococcus could produce as many as 29 different lanthipeptides. But the big surprise came when Cubillos-Ruiz looked at other populations and found that the same organisms, in a different location, produced similarly great numbers of the peptides, “and all of them were completely different,” he says.

After considerable study examining the genomes of many Prochlorococcus cultures and pieces of DNA from the wild, the researchers determined that the way the extraordinary numbers of lanthipeptides evolve is, in itself, something that hasn’t been observed before. While most evolution takes place through tiny incremental changes, while preserving the vast majority of the genetic structure, the genes that enable Prochlorococcus to produce these lanthipeptides do just the opposite. They somehow undergo dramatic, wholesale changes all at once, resulting in the production of thousands of new varieties of these metabolites.

Cubillos-Ruiz, who is now a postdoc at MIT’s Institute For Medical Engineering and Science, says the way these genes were changing “wasn’t following classic phylogenetic rules,” which dictate that changes should happen slowly and incrementally to avoid disruptive changes that impair function. But the story is a bit more complicated than that: The specific genes that encode for these lanthipeptides are composed of two parts, joined end to end. One part is actually very well-preserved across the lineages and different populations of the species. It’s the other end that goes through these major shakeups in structure. “The second half is amazingly variable,” he says. “The two halves of the gene have taken completely different evolutionary pathways, which is uncommon.”

The actual functions of most of these thousands of peptides, which are known as prochlorosins, remain unknown, as they are very difficult to study under laboratory conditions. Similar compounds produced by terrestrial bacteria can serve as chemical signaling devices between the organisms, while others are known to have antimicrobial functions, and many others serve purposes that have yet to be determined. Because of the known antimicrobial functions, though, the team thinks it will be useful to screen these compounds to see if they might be candidates for new antibiotics or other useful biologic products.

This evolutionary mechanism in Prochlorococcus represents “an intriguing mode of evolution for this kind of specialized metabolite,” Cubillos-Ruiz says. While evolution usually favors preservation of most of the genetic structure from the ancestor to the descendants, “in this organism, selection seems to favor cells that are able to produce many and very different lanthipeptides. So this built-in collective diversity appears to be part of its function, but we don’t yet know its purpose. We can speculate, but given their variability it’s hard to demonstrate.” Maybe it has to do with providing protection against attack by viruses, he says, or maybe it involves communicating with other bacteria.

“Prochlorococcus is trying to tell us something, but we don’t yet know what that is,” says Chisholm, who has joint appointments in MIT’s departments of Civil and Environmental Engineering and Biology. “What [Cubillos-Ruiz] uncovered through this molecule is an evolutionary mechanism for diversity.” And that diversity clearly must have very important survival value, she says: “It’s such a small organism, with such a small genome, devoting so much of its genetic potential toward producing these molecules must mean they are playing an important role. The big question is: What is that role?”

In fact, this kind of process may not be unique — it may be just that Prochlorococcus, an organism that Chisholm and her colleagues initially discovered in 1986 and have been studying ever since, has provided the wealth of data needed for such an analysis. “This might be happening in other kinds of bacteria,” Cubillos-Ruiz says, “so maybe if people start looking into other environments for that kind of diversity,” it may turn out not to be unique. “There are some hints it happens in other [biological] systems too,” he says.

Christopher Walsh, emeritus professor of biological chemistry and molecular pharmacology at Harvard University, who was not involved in this work, says “The dramatic diversity of prochlorosins assembled by a single enzyme … raises surprising questions about how evolution of thousands of cyclic peptide structures can be  accomplished by alterations that favor large changes rather than incremental ones.”

According to Schmidt, “There are many possible practical applications. The first is fairly clear: By using this natural variation, the same process can be used to design and build chemicals that might be drugs or other materials. More fundamentally, by understanding the natural process of generating chemical diversity, this will help to create methods to synthesize desired applications in cells.”

The research team also included former graduate student Jessie Berta-Thompson and postdoc Jamie Becker at MIT. The work was supported by the Gordon and Betty Moore Foundation, the National Science Foundation, and the Simons Foundation.

Pew recognizes four MIT researchers for innovation in biomedical science

Biophysicist Ibrahim Cissé and cell biologist Gene-Wei Li honored as Pew Scholars; postdocs Ana Fiszbein and María Inda are named Pew Latin American Fellows.

Julia C. Keller | School of Science
June 20, 2017

The Pew Charitable Trusts has named Ibrahim Cissé, assistant professor of physics, and Gene-Wei Li, assistant professor of biology, as 2017 Pew Scholars in the Biomedical Sciences. In addition, two postdocs, Ana Fiszbein and María E. Inda, were named to the 2017 class of Pew Latin American Fellows in the Biomedical Sciences in computational biology and synthetic biology, respectively.

The Pew Scholars program encourages early-career scientists to pursue innovative research to advance the understanding of human biology and disease. This year, 22 Pew Scholars will receive $240,000 over four years and gain inclusion into a select community of scientists that includes three Nobel Prize winners, five MacArthur Fellows, and five recipients of the Albert Lasker Medical Research Award. The applicants, who conduct research in all areas of biomedical sciences, must be nominated by one of 180 invited institutions. To date, the program has invested in more than 900 scholars.

“Pew’s biomedical programs not only provide young scientists with the flexibility to pursue creative ideas; they also spark interdisciplinary thinking and collaborations that can open new paths in the search for answers,” says Craig C. Mello, who won the 2006 Nobel Prize for physiology or medicine, was a 1995 Pew Scholar, and chairs the Pew Scholars National Advisory Committee.

Cissé, the MIT Class of 1922 Career Development Assistant Professor, says “support from Pew at an early stage is great encouragement in pushing my lab further at the frontiers of different fields.”

Cissé’s research group is investigating the fundamental processes involved in gene activation. Using a combination of techniques in cell and molecular biology, biochemistry, genomics, and super-resolution microscopy, he will continue his investigations of the behaviors of the enzyme involved in the transcription of DNA to RNA molecules. The enzyme, RNA polymerase II, has been well-studied in vitro, but Cissé’s work looks at these transient biological interactions within living cells. His findings will deepen the understanding of these processes, disruptions in which are linked to human disease, including most cancers.

Li’s research looks at evolution of cells’ production of proteins to answer a fundamental biological question of how cells specify how much of each type of protein to produce. In Li’s Quantitative Biology Lab, researchers have developed a technique for measuring the precise production rates of every protein in a cell. Combining this approach with other techniques in cell, molecular, and computational biology, Li is comparing a broad range of organisms across evolutionary distances to determine whether all of their proteins are maintained at some preferred level. By artificially perturbing the quantities of selected proteins, Li can explore the mechanisms cells use to reestablish the proper protein balance to better understand when misregulation occurs that leads to disease.

“The success of my research hinges on close integration between expertise in biological and physical sciences, as well as constant stimulation from both disciplines,” says Li, the Helen Sizer Career Development Assistant Professor. “The Pew scholarship will also provide a unique opportunity to interact with the brightest young minds in the biomedical sciences outside my field that will elevate my research to unanticipated levels.”

Each year, current scholars come together to discuss their research and learn from peers in fields outside of their own. “I am looking forward to interacting with other Pew scholars, many of whom are also working on paradigm-shifting ideas,” says Cissé.

Rebecca W. Rimel, president and CEO of The Pew Charitable Trusts calls the scholars an “impressive group” that has demonstrated “the curiosity and courage that drive great scientific advances, and we are excited to help them fulfill their potential.”

The Pew Latin American Fellows program, meanwhile, is intended to support postdocs from Latin America. Winners are awarded two years of funding to conduct research at laboratories and academic institutions in the United States.

The program also provides additional funding to awardees who return to Latin America to launch their own research labs after the completion of their fellowships. About 70 percent of program participants have taken advantage of this incentive and are conducting work on regional and global health challenges in nine Latin American countries, according to The Pew Charitable Trusts.

“Almost 150 young scientists have returned to their home countries and established independent research labs, providing critical groundwork for biomedical research across Latin America,” says Torsten N. Wiesel, the 1981 Nobel laureate in physiology or medicine and chair of the Latin American Fellows National Advisory Committee.

Ten Pew Latin American Fellows were named this year. The fellowship provides a $30,000 salary stipend to support two years of research, as well as an additional $35,000 for laboratory equipment should the fellow return to Latin America to start his or her own lab. Since the program’s inception in 1990, the program has supported almost 150 young Latin American scientists.

Ana Fiszbein is a postdoc working in the Burge Lab, where she researches the role that changes in gene splicing could play in the biology of normal and tumor cells, with the goal of revealing novel targets for cancer therapeutics. “I am very honored to receive this award, it is a privilege and also a responsibility,” she says. Fiszbein is working with Professor Christopher B. Burge, of the departments of Biology and Biological Engineering and the Broad Institute of MIT and Harvard.

“Ana is an exceptionally talented molecular biologist and independent thinker who came to my lab very well trained from her PhD in Alberto Kornblihtt’s lab,” Burge says. “She has developed very interesting hypotheses about the mechanistic connections between transcription and RNA splicing.”

The activity of genes can be regulated on many levels, including how often DNA is read to produce an RNA, where within the gene that reading begins, and which of the gene’s segments are represented in the RNA molecules that ultimately direct the formation of protein. Tumor cells harbor genetic changes that can alter all three of these points of control. However, little is known about the control of these regulatory processes or how they might be interconnected. Fiszbein is working on a sequence study of RNA in different species, with a sequence analysis of human cancer genomes to identify RNAs that may be present more often in cancer cells. She will then assess whether those RNA segments are co-regulated with the sites where the reading of a gene begins.

Inda is a postdoc working in the lab of Timothy Lu, an assistant professor leading the Synthetic Biology Group in the departments of Electrical Engineering and Computer Science and Biological Engineering. In the Lu Lab, she will work on the development of novel noninvasive strategies, for the early diagnosis and alleviation of inflammation in intestinal disorders, such as inflammatory bowel disease (IBD).

“The fellowship provides me a unique opportunity to learn the practical and theoretical underpinnings of cutting-edge research in the synthetic biology field for diagnosis and treatment of serious ailments,” she says.

A variety of bacteria inhabit healthy human intestines, and members of the Lu laboratory have been working to commandeer some of these microbes for use as sentinels that could patrol the gut and secrete therapeutic molecules in areas that appear inflamed. Inda plans to equip bacteria with biosensors that recognize the molecular markers of IBD — and then trigger the release of anti-inflammatory compounds. She will then assess the engineered microbes’ ability to distinguish between diseased and healthy tissue and to treat inflammation in an animal model of IBD.

Wiesel has high praise for the quality of this year’s Latin American Scholars. “The 2017 class is again made up of researchers of outstanding promise who will no doubt continue to enhance the growing biomedical research community in the region,” he says.