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DSB Retreat
Members of the Dennis Vitkup Lab, from l to r: Konstatine Tchourine, German Plata and Jon Chang (Credit: Sandra Squarcia); Photo Gallery of the retreat.

Innovative research projects were highlighted at the Department of Systems Biology’s annual retreat, held October 5, at Wave Hill Public Garden and Cultural Center in Riverdale, NY. The retreat, attended by 160 faculty, staff, post-doctoral scientists, students and guests, also provided an opportunity for young investigators to showcase their work during a poster competition. 

Andrea Califano , Dr., chair of the department, opened the day’s sessions with welcome remarks, as the retreat also served as a site visit by the National Cancer Institute for the Columbia University Center for Cancer Systems Therapeutics (CaST) . CaST, co-directors Drs. Califano and Barry Honig , vice-chair of the department, was established in 2016 as one of the key centers in the NCI’s Cancer Systems Biology Consortium (CSBC). The initiative behind CSBC is heavily grounded on innovation—bringing together interdisciplinary teams of clinical and basic cancer researchers with physical scientists, engineers, mathematicians and computer scientists who collaborate to tackle major questions in cancer biology from a novel out-of-the-box point of view. 

 

Andrea Califano
Andrea Califano, Dr.

Andrea Califano , Dr., a pioneer in the field of systems biology and founding chair of the Department of Systems Biology at Columbia University Irving Medical Center (CUIMC), has been elected to the National Academy of Medicine (NAM) . Membership in the NAM is considered one of the highest honors in the fields of health and medicine and recognizes individuals who have demonstrated outstanding professional achievements and commitment to service.  

A physicist by training, Dr. Califano has taken innovative, systematic approaches to identify the molecular factors that lead to cancer progression and to the emergence of drug resistance at the single-cell level. Directing the conversation about cancer research away from focusing solely on gene mutations, Dr. Califano examines the complex and tumor-specific molecular interaction networks that determine cancer cell behavior. Using information theoretic approaches, analysis of these networks can precisely pinpoint master regulator proteins that are mechanistically responsible for supporting tumorigenesis and for implementing tumor cell homeostasis. Dr. Califano and his lab have shown that master regulators represent critical drivers and tumor dependencies, despite the fact that they are rarely mutated or differentially expressed, thus establishing them as a bona fide new class of therapeutic targets.

October 10, 2018

Q+A with Dr. Laura Landweber

Oxytricha

Oxytricha. (Credit: Bob Hammersmith)

Laura Landweber, PhD, loves a challenge. So it’s no surprise that she has built a scientific career unraveling the hows and whys of a unique single-cell organism known for its biological complexity.  

An evolutionary biologist whose work sits at the interface of genetics and molecular biology, Dr. Landweber, for nearly 20 years, has focused much of her research on Oxytricha trifallax , a microbial organism that is prevalent in ponds, feeds on algae and has a highly complex genome architecture, making it an attractive, albeit challenging, model organism to study. Compared to humans, with 46 chromosomes containing some 25,000 genes, Oxytricha is known to comprise many thousands of chromosomes, in the ballpark of 16,000 tiny “nanochromosomes”. Yet not only is it complex in sheer numbers of chromosomes but the information carried in those individual chromosomes can be scrambled, like information compression, and the process of development in Oxytricha must descramble this information so that it can be converted into RNA and proteins.

“DNA can be flipped and inverted in Oxytricha and the cellular machinery actually knows how to restore order,” says Dr. Landweber. “Hence, it’s this wonderful paragon for understanding genome integrity and the maintenance and establishment of genome integrity.” 

Even more perplexing, in cell division, Oxytricha reproduces asexually when it wants to produce more in number, and it reproduces sexually when it needs to rebuild its genome. It also has the ability to “clean up” its genome, so to speak, eliminating nearly all of the non-coding DNA, or so-called junk DNA. Much of why Oxytricha presents such an intricate genomic landscape remains a mystery, and for Dr. Landweber, the leading expert on this single-celled protist, that wide-open field for potential discovery is what got her hooked. 

Scientists stunted the puberty of male worms by starving them before they underwent sexual maturation. In the study, published in Nature and led by Oliver Hobert,PhD, researchers suggested that stress from starvation even days before sexual maturation prevented normal changes in the wiring patterns of key neuronal circuits, which caused adult male worms to act immature.

“We found that environmental stress can permanently and profoundly impact the connectivity of a developing nervous system,” said Dr. Hobert, professor of biological sciences at Columbia University and a faculty member of the Department of Systems Biology.

The researchers’ results also suggested that these responses to stress were, in part, controlled by serotonin, a neurotransmitter associated with depression in humans.

Initially, Emily Bayer, a graduate student in the Hobert Lab and co-author of the work, stressed out immature worms when she accidentally left them unattended for a few weeks. This caused the worms to pause their normal growth and enter what scientists call a “dauer state.”

Eventually, Bayer returned the worms to their normal environment and let them grow into adults. After examining the nervous systems of stressed worms, she noticed something unusual. Normally, some of the neuronal connections in the males’ tails are eliminated, or pruned, during sexual maturation. Instead, she found that immature connections in the stressed worms remained. Follow-up experiments suggested that this was strictly caused by starvation and no other forms of stress – such as heat – could have caused the dauer state.

“I was totally surprised. In fact, I never thought stressing the worms out would matter,” said Bayer. 

She also found that starvation before sexual maturation caused male adult worms to act immaturely during behaviors known to be controlled by these circuits. Unlike normal adult males, the stressed worms were highly sensitive to a noxious chemical called SDS. Stressed worms swam away from SDS while normal males barely responded. The stressed worms also had problems mating. Specifically, they spent much less time in contact with hermaphrodite worms than normal males.

Brian Ji Vitkup Lab
Brian Ji won Best Oral Presentation at Biennial Integrated Program Retreat; Visit the gallery for photos from the event.

Brian Ji , a combined MD/PhD student in Columbia’s Department of Systems Biology, delivered the winning oral presentation at the recent Biennial Integrated Program Retreat. Ji, who is a member of the Vitkup Lab, presented “Quantification of Human Gut Microbiota Variability Using Replicate Sampling,” and was one of six systems biology graduate students who delivered research presentations at the conference. 

Ji discussed a novel experimental and computational method he has developed to understand spatiotemporal dynamics of the human gut microbiome, as well as the technical noise tied to current human microbiome sequencing techniques. In addition to the human gut, the method, he says, is broadly applicable to other bacterial ecosystems and other sequencing-based studies. In the Vitkup Lab , Ji works on developing and utilizing quantitative approaches to reveal novel biological insights into bacterial ecology as well as cell physiology. His research interests also include exploring computational models and tools to study cancer metabolism at a global scale. In 2011, Ji received a prestigious Barry Goldwater Scholarship for his work on mathematical modeling to study impaired brain connectivity in epilepsy.