Each cell needs to constantly remodel the landscape of its surface because the thin membrane that surrounds all cells is fragile and must be renewed to protect the cell from lysis and death.
And that’s where the trouble begins.
To remove aged and damaged cell-surface proteins, the membrane-sculpting macromolecular machine creates vesicles. These vesicles function as “molecular trash bags,” which carry old and misfolded membrane proteins from the surface into internal recycling plants, where the waste is degraded and components are reused.
That’s why Shaogeng Tang – a fourth-year doctoral student in the field of biochemistry, molecular and cell biology and recent recipient of the Harry and Samuel Mann Outstanding Graduate Student Award – is studying the ways these machines assemble and function to learn how to switch them on and off.
Tang’s research centers on ESCRT (Endosomal Sorting Complex Required for Transport) machinery that creates vesicles to remove waste. If these “trash bags” are unable to make their deliveries, cellular waste accumulates, resulting in the development of neurodegenerative diseases as well as cancer. Human immunodeficiency virus, HIV, hijacks the ESCRTs to burst out of the infected cells, and progressively destroys the body’s immune system, which causes AIDS.
Tang has been investigating how the ESCRT machinery packages cellular waste inside a piece of the cell’s membrane and “bud off” tiny “trash bags” by sorting out bad membrane proteins from good ones, which essentially requires the inactive ESCRT monomer to convert into an active polymer that sequesters the membrane waste and deforms the membranes.
“If you can find a way to have the protein always in this inactive shape, a virus like HIV will never release from the infected cell,” Tang said.
For the last three years, Tang has worked in the Emr Lab, which studies the regulation of cell signaling pathways under the leadership of Scott D. Emr, the Frank H.T. Rhodes Class of ’56 Director of the Weill Institute for Cell and Molecular Biology and professor in the Department of Molecular Biology and Genetics.
Tang brings a multidisciplinary approach to his research, thanks to his background as a chemist; he earned a bachelor’s degree in pharmacy at Peking University in Beijing. But Tang’s interest in investigating the underlying mechanisms of disease stretches back to his days as a middle-school student.
“In 2003 there was a SARS outbreak in China so everything, all the schools, the government, the industries were shut down. At the time people were in fear because we had no idea what was the cause of this disease,” said Tang, whose mother is also a biochemist. “That was something that really triggered my curiosity about knowing more about how these viruses affect the cells.”
The Harry and Samuel Mann Outstanding Graduate Student Award was established by Thomas Mann ’64 and Diann Mann ’66, and Cornell parents Jeanne and Gary Newman. Cousins Thomas and Jeanne conceived of the $20,000 award as a way to honor their fathers, Harry and Samuel Mann, the sons of Russian immigrants who were early innovators in the production of penicillin, by celebrating the next generation of biochemical, molecular and cell biologists.
“Our fathers believed strongly in the value of learning, a passion for the highest level life science research, as well as the importance and the value of hard work,” said Thomas Mann, Samuel's son. “Shaogeng Tang certainly exemplifies these values. We wish him great success as he pursues his passion.”
“The award really motivates me to continue my best in my thesis research, but it also inspires me to follow the Mann family’s example of doing science communication and community service,” Tang said.
Emr praised Tang for the key contributions he has made to understanding ESCRT-mediated protein sorting, his passion for science, his imaginative problem-solving approaches, as well as his enthusiasm seeking out interdisciplinary collaborations.
And Tang is equally ambitious outside the lab, too. A figure-skating enthusiast, he participated in the music selection and program choreography for the Chinese Olympic team.
David Nutt is a writer for the College of Agriculture and Life Sciences.