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Systems Biology and Women's Health: A Q+A with Tal Korem, PhD

As a member of Columbia University’s Program for Mathematical Genomics (PMG) , Tal Korem, PhD, is bringing his interests in systems biology, quantitative research, and the human microbiome to areas of clinical relevance. For Dr. Korem, that clinical focus is women’s reproductive health. 

“There is still a lot we don’t understand that relates to women’s health, to fertility, and to birth outcomes, and how microbes play a role in all of this,” says Dr. Korem, assistant professor of systems biology, with a joint appointment in obstetrics and gynecology at Columbia University Vagelos College of Physicians and Surgeons. A current focus of the Korem lab is preterm birth, i.e., birth that occurs prior to 37 weeks of gestation, though Dr. Korem intends to expand into other areas such as infertility and endometriosis. 

Tal Korem, PhD
Tal Korem, PhD

Dr. Korem’s interest in  women’s health research is personal, stemming from several impactful experiences that hit close to home. 

“My aunt passed away from ovarian cancer and I have seen friends and family members struggle with idiopathic infertility,” he says. “Also, witnessing the complications with the birth of my first child, which involved emergency procedures, motivated my interest in this area, and I am very excited about the potential to contribute to women’s health with my own research.” 

Dr. Korem, a native of Tel Aviv, Israel, is the first in his family to earn a PhD, and had entered academia as a medical student. After completing  his undergraduate degree, he enrolled in a MD/PhD graduate program. There, he realized that research was what he enjoyed the most. He is a trained computational biologist, and studied under Professor Eran Segal at the Weizmann Institute of Science, where his work focused on the  human microbiome, a complex system of microbial communities that inhabit every body part. 

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Personalized Gene Delivery to the Gut

MAGIC - Wang Lab

Illustrated here: (a) In contrast to traditional approaches to cultivate microbes first and then test for genetic accessibility, MAGIC harnesses horizontal gene transfer in the native environment to genetically modify bacteria in situ. (b) MAGIC implementation to transfer replicative or integrative pGT vectors from an engineered donor strain into amenable recipients in a complex microbiome. Replicative vectors feature a broad-host range origin of replication (oriR), while integrative vectors contain a transposable Himar cassette and transposase. The donor E. coli strain contains genomically integrated conjugative transfer genes (tra) and a mCherry gene. Transconjugant bacteria are detectable based on expression of an engineered payload that includes GFP and an antibiotic resistance gene (abr).

A team of researchers, led by Dr. Harris Wang of the Department of Systems Biology , has engineered bacteria to benefit and improve the overall health of our gut microbiome. In a proof-of-concept paper published in Nature Methods , Dr. Wang and his team demonstrate MAGIC, an innovative gene delivery system that ‘hacks’ the gut microbiome to perform any desired function, from harvesting energy from food and protecting against pathogen invasion to bolstering anti-inflammatory properties and regulating immune responses.

“The MAGIC system allows us to insert new gene functions directly into an existing microbiome without permanently altering the composition of the microbiome as a whole,” says Sway Chen , an MD/PhD student in the Wang lab and co-author of the study.

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Sampling Neighborhoods of the Gut Microbiome

The gut microbiome–composed of hundreds of different species of bacteria–is a complex community and a challenge for scientists to unravel. One specific challenge is the spatial distribution of different microbes, which are not evenly distributed throughout the gut. A new method developed by the lab of Dr. Harris Wang should help scientists locate and characterize these neighborhoods, which could shed light on how microbes influence the health of their hosts.

Techniques that can identify all species in the gut microbiome only work with homogenized samples (like stool), but methods that preserve spatial information can only cope with a handful of species.

Dr. Wang, assistant professor of systems biology and of pathology & cell biology, and graduate student Ravi Sheth in the Department of Systems Biology, tested the new technique with mice who switched from a low-fat to a high-fat diet. Diet is known to change the abundance of specific bacteria in the gut within days, but the new technique also revealed that the switch caused wholesale changes of microbial neighborhoods.

“Specific regions of bacteria were entirely lost with a switch in diet,” Sheth says. “This was exciting to us as it will give us clues to understanding how that change happens and how the change may impact health.”

Read the full article in the CUIMC Newsroom. 

The research, titled “Spatial metagenomic characterization of microbial biogeography in the gut,” was published July 22 in Nature Biotechnology.

 

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Grad Spotlight: Brian Ji, PhD

Brian Ji_2
Systems Biology Graduate Brian Ji, PhD

For Brian Ji, the big draw to systems biology stemmed from his passion for applying quantitative approaches to understanding biology. While an undergraduate at the University of Wisconsin-Madison, Ji studied nuclear engineering and credits that training for the way in which he tackles scientific questions: creatively, and as a problem solver. 

“There is no one right approach to asking a question and setting out to answer it, and that freedom is what makes science fun for me,” he says. 

Ji studied under Dr. Dennis Vitkup in the Vitkup lab and completed his thesis defense for systems biology in the fall of 2018.  Also an MD student in Columbia’s Vagelos College of Physicians and Surgeons , Ji was attracted to Columbia because of the close interplay between the Systems Biology Department and the Columbia University Irving Medical Center. “Ultimately,” he says, “the opportunity to sit at the intersection between math, biology and medicine was too good to pass up.”

Ji’s PhD work focused on understanding spatiotemporal dynamics of human gut microbiota. He developed several frameworks that leveraged the increasing availability of high-throughput sequencing data to better understand and precisely quantify patterns of human gut microbiota variability across time and space. His work showed that characterizing dynamics—changes in bacterial abundances in our gut—are critical to understanding how these ecosystems function and is highly connected to multiple factors such as host diet, travel and diet. 

Ji also spent part of his PhD studying limitations of cancer cell growth in different environmental conditions. He credits Columbia for exposing him to a variety of research topics. 

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Same Microbe, Different Effect

The Korem Lab

One of the structural variations detected in Anaerostipes hadrus, which is deleted in ~40% of the population (top), and associated with higher disease risk. Genes in this region (bottom) code a composite inositol catabolism - butyrate production pathway, potentially supplying the microbe with additional energy while supplying the host with butyrate, previously shown to have positive metabolic and anti-inflammatory effects. (Credit: Korem lab)

Our gut microbiome has been linked to everything from obesity and diabetes to heart disease and even neurological disorders and cancer. In recent years, researchers have been sorting through the multiple bacterial species that populate the microbiome, asking which of them can be implicated in specific disorders. But a paper recently published in Nature addressed a new question: "What if the same microbe is different in different people?" The study was co-led by Dr. Tal Korem , assistant professor of systems biology and core faculty member in the Program for Mathematical Genomics at Columbia University Irving Medical Center . 

It has been long known that the genomes of microbes are not fixed from birth, as ours are. They are able to lose some of their genes, exchange genes with other microorganisms, or gain new ones from their environment. Thus, a detailed comparison of the genomes of seemingly identical bacteria will reveal sequences of DNA that occur in one genome and not others, or possibly sequences that appear just once in one and several times over in others. These differences are called structural variants. Structural variants - even tiny ones - can translate into huge differences in the ways that microbes interact with their human hosts. A variant might be the difference between a benign presence and a pathogenic one, or it could give bacteria resistance to antibiotics.

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Harris Wang Named 2018 Schaefer Scholar

Harris Wang in Lab

Harris Wang, PhD, assistant professor of systems biology, has been named a 2018 Schaefer Research Scholar for his novel approach to explore the role that bacteria cells in our gastrointestinal tract play on the efficacy of drug therapies.

Dr. Wang, who has a joint appointment in the Department of Pathology and Cell Biology, develops new tools and platforms to determine how genomes in microbial populations form, maintain themselves, and change over time, across many environments. His goal is to use synthetic biology approaches to engineer ecologies of microbial populations, such as those found in the gut and elsewhere in the human body, in ways that could improve human health.

The project that won the support of the Schaefer Scholars Research program centers on developing a platform approach to systematically determine new mechanisms by which specific members of the human microbiome metabolize and alter drugs and pharmaceuticals. Dr. Wang and his group intend to evaluate the impact of the microbiome on drug efficacies using cellular and animal models, focusing on the gut microbiome—an important and underexplored area of research.

“There have been studies that suggest a key link between microbes and their role altering the efficacy of drug treatments,” says Dr. Wang, “but this area of research is unchartered territory, and there is more knowledge to be gained by pinpointing how a person’s microbiome could metabolize specific therapeutics by inactivation, degradation, or alteration of its chemical structures. The large-scale data generated from our project could improve drug prescriptions and clinical trials by reducing failures and classifying patients based on otherwise unknown yet important microbiome-drug interactions.”

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Harris Wang Named Recipient of Presidential Early Career Award for Scientists and Engineers

Harris WangHarris Wang

Harris Wang has been named a recipient of the prestigious Presidential Early Career Award for Scientists and Engineers (PECASE). Dr. Wang is among 102 researchers recognized today by President Barack Obama as the newest recipients of this honor.

The PECASE is considered the United States’ highest award for young scientists and engineers, conferred annually at the White House at the recommendation of participating federal agencies. The award celebrates young researchers at the beginning of their independent research careers who show exceptional promise to lead at the frontiers of twenty-first century science and technology.

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Systems Biology Scientists Help Expand Microbiome Research at Columbia

Staphylococcus epidermis
Interactions between human cells and the bacteria that inhabit our bodies can affect health. Here, Staphylococcus epidermis binds to nasal epithelial cells. (Image courtesy of Sheetal Trivedi and Sean Sullivan.)

Launched in 2014 by investigators in the Mailman School of Public Health, the CUMC Microbiome Working Group brings together basic, clinical, and population scientists interested in understanding how the human microbiome—the ecosystems of bacteria that inhabit and interact with our tissues and organs—affects our health. Computational biologists in the Department of Systems Biology have become increasingly involved in this interdepartmental community, contributing expertise in analytical approaches that make it possible to make sense of the large data sets that microbiome studies generate.

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Wang Lab Work on Bioeconomics Featured in Wall Street Journal

Economic Markets and Biological Markets

In a similar manner to the ways in which countries make and trade goods, microbial cells within bacterial communities exchange metabolites to promote cell growth. This perspective could provide a way of studying microbial communities from the perspective of economics.

An article in the Wall Street Journal reports on a recent collaboration involving Columbia University Department of Systems Biology Assistant Professor Harris Wang and Claremont Graduate University economist Joshua Tasoff that identified some intriguing similarities between economic markets and the exchange of resources among microbes within bacterial communities. 

In an unusual marriage, biology and economics appear to be a match made in heaven.

Four years ago, two former roommates reunited at a friend’s wedding had time to catch up. The first, an economist, asked: “What are you working on?” The second, a biologist, answered: “How microbial communities interact. It’s kind of like in economics.”

And that’s when the intellectual sparks began to fly.

Turns out microbial communities—what most of us think of as germs—expand by trading metabolites such as amino acids with other species of bacteria, just like free-market economies grow by exchanging goods and services.

That novel insight, inspired by a chance conversation and supported with research developed over the intervening years, provides a framework to explain how different species of bacteria interact in complex communities.

You can read the entire article here: Economies of Ail: How Bacteria Flourish. [login may be required]

Related publication

Tasoff J, Mee MT, Wang HH. An economic framework of microbial trade. PLoS One. 2015 Jul 29;10(7):e0132907.

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Harris Wang Named Office of Naval Research Young Investigator

Gut-Brain Microbiota
A grant from the Office of Naval Research will support the development of three foundational synthetic biology technologies for engineering the human gut microbiota.

Harris Wang, an assistant professor in the Columbia University Department of Systems Biology, has been selected for the Office of Naval Research 2015 Young Investigators Program. This highly selective program promotes the development of early-career academic scientists whose research shows exceptional promise and creativity. With the support of this award, Dr. Wang will extend his research in the field of synthetic biology to develop new technologies for engineering the gut microbiome, the ecosystem of bacteria that inhabit the human digestive system. These new methods, Wang anticipates, could provide new ways of designing communities of different microbial species and ultimately modulating interactions between the gut, the immune system, and the brain.

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Functional Metagenomics Enables First Study of Bacterial Fitness in the Gut Microbiome

Gut bacteria

Photo by David Gregory and Debbie Marshall, Wellcome Images. 

Recent deep sequencing studies are providing an increasingly detailed picture of the genetic composition of the human microbiome, the diverse collection of bacterial species that inhabit the gut. At the same time, however, little is known about the dynamics of these colonies, particularly why certain microbial strains outcompete others in the same environment. In a new paper published in the journal Molecular Systems Biology, Department of Systems Biology Assistant Professor Harris Wang, in collaboration with Georg Gerber and researchers at Harvard University, report on their development of the first method for using functional metagenomics to identify genes within commensal bacterial genomes that give them an evolutionary fitness advantage.

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New Directions in Genome Engineering: An Interview with Harris Wang

Harris Wang

As a graduate student in George Church’s lab at Harvard University, Harris Wang developed MAGE, a revolutionary tool for the field of synthetic biology that made it possible to introduce genomic mutations into E. coli cells in a highly specific and targeted way. Now an Assistant Professor in the Columbia University Department of Systems Biology, Dr. Wang recently published a paper in ACS Synthetic Biology that introduces an important advance in the MAGE technology. The new technique, called (MO)-MAGE, uses microarrays to engineer pools of oligonucleotides that, once amplified and integrated into a genome, can generate thousands or even millions of highly controlled mutations simultaneously. This new method offers a cost-effective way for designing and producing large numbers of genomic variants and provides an efficient platform for experimentally exploring genome-wide landscapes of mutations in bacteria and optimizing the organisms’ biochemical capabilities.

In the following interview, Dr. Wang explains the origins of the new technology, and discusses what he sees as the remarkable potential it holds for both basic biological research and industrial applications of synthetic biology.

How are MAGE and (MO)-MAGE different from more traditional methods in genome engineering?

In traditional genome engineering, researchers would induce genome perturbations randomly. For example, you might use ultraviolet radiation or a mutagen to generate mutations and then do a selection experiment to compare and isolate cells with different genotypes based on how they respond to specific stimuli. The problem with this approach, though, is that you have no way to control what mutations occur, even if you know the mutation you are interested in investigating.

(MO)-MAGE offers a cost-effective and efficient way to simultaneously mutate large numbers of genes in a targeted way.

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