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Protein engineering is a relatively young field that creates new proteins never seen before in nature. Today’s protein engineers usually create synthetic proteins by making small changes to the gene that encodes a naturally occurring protein. The variety of synthetic proteins range from stain-removing enzymes that have improved detergents to a long-acting insulin that’s used by millions of people with diabetes.

But two big unsolved challenges for protein engineers remain: The gene encoding the synthetic protein needs to be contained to prevent escape into other organisms and the gene needs to resist mutating over time so the protein doesn’t lose its function.

By merging two genes into a single DNA sequence, Columbia University synthetic biologists have created a method that could prevent human-engineered proteins from spreading into the wild, as well as stabilize synthetic proteins so they don’t change over time. The work, recently published in Science, was developed by Harris Wang, PhD, assistant professor of systems biology, with graduate student, Tomasz Blazejewski and postdoctoral scientist, Hsing-I Ho, PhD. 

In devising the method, the researchers were inspired by overlapping genes in viruses. When two different genes overlap, they occupy the same sequence of DNA. But the genes are read in different frames so that two different proteins are produced.

In overlapping genes, a random mutation in the sequence may not affect one gene, but it’s likely that it will harm the second gene.

“Overlapping genes essentially lock in a specific DNA sequence, and we thought we could exploit this idea for synthetic biology ...Ten years ago, we didn’t have the technology that would make this possible,” says Dr. Wang. “We didn’t have enough sequences in the database to make informed predictions and we didn’t have a way to synthesize long DNA sequences for testing our predictions.”

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.

 

Newly Tenured Faculty
Awarded tenure this year in the Department of Systems Biology, left to right: Dr. Nicholas Tatonetti, Dr. Yufeng Shen, and Dr. Chaolin Zhang.

Congratulations to Drs. Yufeng Shen, Nicholas Tatonetti, and Chaolin Zhang of the Department of Systems Biology, who have been awarded tenure and promoted to associate professor. Their new appointments are effective July 1, 2019. 

Yufeng Shen, PhD

Dr. Shen joined Columbia University Irving Medical Center in 2011 as an Assistant Professor in Systems Biology and Biomedical Informatics. He directs a research group focused on studies of human biology and diseases using genomic and computational approaches. They are developing new methods to interpret genomic variations by machine learning based on biological mechanisms, and using these methods in large-scale genome sequencing studies to identify new genetic causes of human diseases, such as autism, birth defects, and cancer. His group also works on modeling of clonal and transcriptional dynamics of immune cells to improve our understanding of human adaptive immune system under normal and clinical conditions. Dr. Shen serves as an Associate Director of the JP Sulzberger Columbia Genome Center, a member of the Program in Mathematical Genomics, and an adjunct member of Columbia Center for Translational Immunology. 

Nicholas Tatonetti, PhD

Dr. Tatonetti, whose primary appointment is in the Department of Bioinformatics, has an interdisciplinary appointment with both the Departments of Systems Biology and Medicine. Dr. Tatonetti’s lab specializes in advancing the application of data science in biology and health science. His group integrates their medical observations with systems and chemical biology models to not only explain drug effects, but also to gain further understanding of basic biology and human disease.

Dr. Harris Wang of Systems Biology
Dr. Harris Wang is lead PI on a new DARPA-funded project developing novel therapies to counter effects of high-dose ionizing radiation.

Harris Wang, PhD, assistant professor of systems biology at Columbia University Irving Medical Center , is leading a team of experts in radiation research, CRISPR-Cas technologies, and drug delivery on an innovative new project announced June 27 funded by the Defense Advanced Research Projects Agency (DARPA) . The up to $9.5M project focuses on pursuing a therapy to protect the body from the effects of high-dose ionizing radiation, and is part of DARPA's initiative to fund research into new strategies to combat public health and national security threats.

In humans, acute radiation syndrome primarily affects stem cells in the blood and gut, yet existing treatments only help to regenerate blood cells, and only with limited effect. There is no possibility for prophylactic administration of these drugs, and most must be delivered immediately following radiation exposure to provide any benefit. There are no existing medical countermeasures for radiation damage to the gut.

The Columbia team aims to develop an orally delivered programmable gene modulator therapeutic. The multimodal treatment the team envisions would take hold in both the gut and liver, triggering protection and regeneration of intestinal cells, while also inducing liver cells to produce protective cues that trigger the regeneration of blood cells in bone marrow.

Columbia investigators win Chan Zuckerberg Initiative grants to accelerate development of cellular roadmap of the human body.

In two groundbreaking research projects contributing to the Human Cell Atlas, Columbia University scientists are tasked with mapping complete cells in the immune system and the human spine. The global effort is aiming to identify and define every cell type of the human body and create a collection of maps for navigating the cellular basis of human health and disease.

Peter Sims, PhD
Peter Sims, PhD, assistant professor of systems biology

The Columbia teams, which include co-principal investigators from the Department of Systems Biology Drs. Peter Sims and Raul Rabadan , are among the 38 collaborative science teams launching the Chan Zuckerberg Initiative’s (CZI) Seed Networks for the Human Cell Atlas project announced today. The three-year projects, receiving a total of $68 million in award funding by Seed Networks, are collaborative groups that are bringing together expertise in science, computational biology, software engineering, and medicine to support the ongoing progress of the Human Cell Atlas .

Investigating the Immune System + Aging

Dr. Sims, part of an international team including close collaborator Dr. Donna Farber of the Department of Surgery , is combining single-cell sequencing technologies, data analysis, and immunology expertise to better understand how the immune system ages and gain new insights into how human diseases occur.