Isolated from mouse embryos, mouse embryonic fibroblasts (depicted) perform two important roles in stem cell culture: They secrete several important growth factors into the medium, which help maintain pluripotency, and they provide a cellular matrix for cells to grow.
Image courtesy of Joe McKellar.
Meet one of our early-career scientists at Sanford Burnham Prebys Medical Discovery Institute: Jimmy Massenet, PhD, a postdoctoral researcher in the lab of Pier Lorenzo Puri, MD. Massenet studies changes in the way DNA is organized inside muscle cells that contribute to muscle-wasting diseases.
Massenet also is the 2026 recipient of the Fishman Fellowship, which provides exceptional Sanford Burnham Prebys postdocs with a two-year fellowship award. This fellowship is bestowed every other year to the young scientist who is ranked highest by the Fishman Awards selection committee.
When and how did you become interested in science?
I’ve always been very curious about my environment and how things work. This inclination led me to become fascinated in cell biology when I started to study it in school. I found it fascinating seeing how cells function, especially the way everything happens mechanically inside our cells.
As I progressed to university studies, I discovered epigenetics and the way the genome can be changed with transient modifications. I found that so amazing that I wanted to continue in this direction.
What are the key areas of research you focus on?
I’m studying a muscle-wasting disease called myositis. It’s an inflammatory muscular disease that causes patients to develop a progressive inflammation in their muscles. Their muscle size starts to shrink and they lose their strength.
To better understand this disease, I am investigating a protein that is called CTCF. It’s an architect of our DNA genome that works by folding the DNA in loops and allows the creation of a three-dimensional structure in our nuclei. CTCF is altered in patients suffering from myositis and seems to worsen patient outcomes, so it may represent a target for future therapies.
What motivates you about your research?
I like that no two days are the same as a scientist. In this job, we always have new experiments to do. Each day you’re going to learn something new, which I find exciting.
And sometimes you have the absolute thrill of finding something new that no one in the world has discovered before.
What do you like about working here?
I love the team my mentor has assembled in the Puri lab. I worked in the muscle research field before joining Sanford Burnham Prebys and knew I wanted to apply to work here to be a part of this group.
I have worked in France in smaller institutes, and it has given me an appreciation for the technology we have at Sanford Burnham Prebys. Our core facilities here are outstanding and can process samples in a few days that would previously have taken weeks or even months.
What are your career goals?
I want to continue in academia because I like the nature of this job. I enjoy taking the lead on a research project and deciding to pursue a particular direction. My goal then is to open my own lab and continue to focus on chromatin organization.
There are many proteins beyond CTCF that are linked to the three-dimensional structure of the genome that need to be studied. If we can understand how they contribute to disease, I think that will make a real difference in terms of improving the diagnosis of patients as well as potentially the development of new treatments.
What do you enjoy doing when you’re not in the lab?
I love to run, especially trail running, and the San Diego area is amazing for that. I have done some ultra-marathons here and those were very rewarding experiences. I enjoy going to the gym, too, and when I’m home, I dabble in some painting.
Postdocs at Sanford Burnham Prebys are pushing the boundaries of science every day through curiosity, collaboration, and innovation. This series highlights their unique journeys, what inspires their work, and the impact they’re making across our labs.
Michael Karin, PhD, director and professor of the Center for Metabolic and Liver Diseases at Sanford Burnham Prebys, was awarded the American Liver Foundation’s Distinguished Scientific Achievement award on October 28 at the organization’s 50th anniversary National Legacy Gala in New York City.
The award recognized Karin’s longstanding contributions spanning nearly five decades of research focusing on the biological pathways that connect inflammation, metabolic disease, and liver cancer. His research has helped clarify how inflammatory signaling and metabolic stress can drive disease.
“We are so honored to recognize Dr. Karin for his trailblazing research discoveries that have helped illuminate the connections between inflammation, metabolism, and liver disease—connections that open potential paths to preventing and treating steatohepatitis and other metabolic conditions,” said Lorraine Stiehl, chief executive officer of the American Liver Foundation.
“His work reminds us that progress for people living with liver disease begins with the courage to ask fundamental questions and the persistence to follow the evidence. We are proud to acknowledge a scientist whose cutting-edge discoveries continue to inspire the field.”
An induced pluripotent stem cell-derived sensory neuron labeled to show tubulin and actin. Tubulin is a globular protein that serves as the primary building block of microtubules—hollow, cylindrical fibers that form a crucial part of the eukaryotic cytoskeleton. Actin is a vital, highly conserved globular protein that forms the microfilaments of the eukaryotic cytoskeleton and the thin filaments in muscle cells.
Image courtesy of Stella Whittaker, NIH-NINDS.
New computational toolkit helps researchers identify and study cancer-driving DNA alterations, with a public repository of more than 15,000 samples
Extrachromosomal DNA (ecDNA) consists of circular, double-stranded DNA molecules that have separated from chromosomes. They frequently carry multiple copies of cancer-driving oncogenes that are then highly expressed. Thus, ecDNA is increasingly recognized as a particularly worrisome driver of cancers and treatment resistance.
Now, a multi-institutional research team co-led by Jill Mesirov, PhD, Distinguished Professor in the Cancer Genome and Epigenetics Program at Sanford Burnham Prebys, has released AmpliconSuite, a computational toolkit for identifying and characterizing ecDNA and other focal DNA amplifications in cancer genomes, along with Amplicon Repository for hosting and sharing the community’s samples and ecDNA analyses. The repository currently provides public access to results for more than 15,000 samples.
“The combination of these two resources democratizes both the complicated bioinformatic approaches required for identifying ecDNA and elucidating their structure, along with openly communicating the results of employing them,” said Mesirov.
The work is described in the October 16, 2026 online issue of Nature Methods.
Mesirov and colleagues, including co-senior study authors Vineet Bafna, PhD, a professor of computer science and engineering at UC San Diego, and Paul S. Mischel, MD, a professor of pathology at Stanford University, developed computational methods to identify ecDNA and distinguish it from other forms of DNA amplification, and the informatics workflow and platform to share them.
The researchers validated the toolkit using 175 genes examined through fluorescence in situ hybridization across 72 cancer cell lines. The latest classifier achieved 91 percent precision and 95 percent recall in the study’s ecDNA validation analysis. An analysis of 6,506 cancer samples from patients also revealed patterns in which cancer-promoting genes tend to be amplified together on ecDNA.
Jill Mesirov Image credit: Sanford Burnham Prebys.
AmpliconSuite is only the latest of Mesirov’s contributions to advancing biomedical research tools and capabilities. Mesirov has also played a leading role in developing widely used computational biology resources, including Gene Set Enrichment Analysis, the Molecular Signatures Database, and the Integrative Genomics Viewer. Together, these tools help researchers analyze, interpret, and visualize complex genomic data. These resources are used by researchers worldwide in cancer biology and other areas of biomedical science.
False-colored image of dying superficial epithelial cells during osmotic stress, which results in water passing in and out of the cells. These cells act as shields, covering the body’s external and internal surfaces.
Image courtesy of Yue Rong Tan.
The series highlights the groundbreaking work and unique perspectives of women leaders in the biomedical sciences
Sanford Burnham Prebys Medical Discovery Institute hosted another inspirational installment of the Women in Science Lecture Series on October 14, 2026. The featured guest speaker was Robin Toft, CEO of Curebound, a community-powered cancer research accelerator in San Diego that has invested more than $50 million in 170 scientific projects.
Toft shared the trajectory of her career in health care and research. Early in her professional journey as a clinical laboratory scientist, she found that she excelled at educating physicians about new technologies. That led her into molecular diagnostic sales and later into the San Francisco biotech industry. After being diagnosed with colon cancer on a business trip, she was determined to move her life and career in a different direction.
Toft built an executive search firm in San Diego focused on serving oncology companies. Her goal was to put the right people in the right places to succeed. After she grew her search firm and it was acquired, Toft focused even more intently on providing service to institutional boards.
“Having served on more than 15 boards in and around this area, I was pulled toward nonprofit service,” said Toft. “Curebound was by far my favorite, so when Anne Marbarger stepped down as CEO, I raised my hand and said, ‘choose me, I really, really need to do this job.’”
Toft then discussed enhancements to Curebound’s leadership team and fundraising strategies aimed at increasing the organization’s ability to invest in the region.
“We love to invest over $10 million annually, and I want that to go up to 15, 20 and 25 in the coming years,” she said.
Toft concluded by providing advice on career advancement for women in academic and industry science based on her experience placing high-level executives.
“It always comes down to three elements: confidence, competence and connections,” said Toft.
Demonstrating confidence starts with candidates applying to jobs even when they don’t meet every single qualification. Competence includes creating and demonstrating value, then leveraging it to ask for additional opportunities. On the topic of connections, Toft discussed mentors who provide direct guidance and sponsors who go to bat for you when you’re not in the room.
“I challenge each of you to create a board of directors for yourself that includes both mentors and sponsors, and you’ll have a network to push you forward.”
Curebound CEO Robin Toft shared the trajectory of her career in health care and research. She also provided advice on career advancement for women in academic science and industry based on her experience running an oncology-focused executive search firm. Image credit: Sanford Burnham Prebys.
Following Toft’s remarks, Jessica Proulx, PhD, postdoctoral associate in the lab of Peter Adams, PhD, moderated a fireside chat and audience question-and-answer session with Toft, Susanne Heynen-Genel, PhD, director of high content imaging platforms in the Center for Therapeutics Discovery, and Xueqin (Sherine) Sun, PhD, assistant professor in the Cancer Genome and Epigenetics Program at the Sanford Burnham Prebys NCI-designated Cancer Center. Heynen-Genel and Sun have active research projects supported by grants from Curebound.
Topics during the fireside chat included: the importance of funding for high-risk, high-reward research and pilot studies to generate preliminary data; how grantmakers and principal investigators manage risk and balance their professional portfolios; plans for investing in personalized therapy research; and how principal investigators can better serve as mentors and sponsors for female scientists.
The Women in Science Lecture Series features events that are free and open to the public. The series is part of broader efforts at Sanford Burnham Prebys to foster an environment that nurtures the success of individuals from all backgrounds. The events are hosted by the Office of Workforce Engagement & Belonging and highlight the groundbreaking work and unique perspectives of women leaders in the biomedical sciences, while fostering mentorship and collaboration across the Torrey Pines Mesa.
Stay tuned for more information about the next event in the series scheduled for spring 2027.
The only way is up. What appears to be manmade is actually a scanning electron micrograph of a growing calcite crystal. The apparent arrows on the surface are formed by the crystal’s natural growth and the way proteins bind.
Image courtesy of David Green.
What appears to be some sort of horrific deep-sea creature is, in fact, the microscopic image of Taenia solium, a species of pig tapeworm that can cause human infections if it or its eggs are consumed in undercooked pork. What appear to be eyes and mouth are actually suckers and a hook-lined rostellum used to grip and anchor to the wall of the human small intestine.
Image courtesy of Teresa A. Zgoda.
The Dr. Herbert Wertheim Trust for Humanity has announced the Wertheim Laureate Prize, which invites eligible recipients of the Nobel Prize in Physiology or Medicine each year to individually direct $1 million to causes they believe will do the most good.
In its inaugural year, three 2026 recipients—Karl Deisseroth, Peter Hegemann, and George Nagel—were honored for their work developing optogenetics, a technique that uses light to control individual nerve cells in the brain. The trio, announced October 5, will share a Nobel prize of 12 million Swedish crowns ($1.2 million).
The Wertheim Laureate Prize rests on a simple idea, according to the Trust: “The scientists the world has just honored for transforming medicine and physiology are among the best judges of where philanthropy can make the greatest difference.”
