Molecular imaging researcher shares 2008 Nobel Prize for chemistry

October 14, 2008

Molecular imaging researcher Roger Tsien, Ph.D., has been awarded the 2008 Nobel Prize in Chemistry with two other American scientists for the discovery of green fluorescent protein and the creation of fluorescent molecules that are often used to track subcellular structures during in vivo molecular imaging.

Molecular imaging researcher Roger Tsien, Ph.D., has been awarded the 2008 Nobel Prize in Chemistry with two other American scientists for the discovery of green fluorescent protein and the creation of fluorescent molecules that are often used to track subcellular structures during in vivo molecular imaging.

A professor of chemistry and biochemistry at the University of California, San Diego, Tsien shares the prize with Osamu Shimomura, Ph.D., of the Marine Biological Laboratory in Woods Hole, MA, and Boston School of Medicine and Martin Chalfie, Ph.D., of Columbia University in New York City. All three were honored for the discovery of green fluorescent proteins and subsequent developments that led to its use as a tagging tool in bioscience. The recipients of the 2008 award were announced Oct. 8.

"It's a great day for molecular imaging," said Dr. Christopher Contag, a molecular imaging scientist who collaborates with Tsien from Stanford University. "Molecular imaging really grew out the need to develop reporter genes and reporter molecules for use in vivo. Green fluorescent protein and its related proteins are perfect examples of that."

Tsien and colleagues in his UCSD laboratory have engineered mutations of the original green fluorescing proteins that make jellyfish and corals glow in the dark. Tsien helped demonstrate that the fluorescing molecules could pass through the membranes of targeted cells to monitor and image several molecular processes simultaneously without disrupting cellular functions. To boast their versatility, Tsien developed a color palette of fluorescing molecular dyes ranging from ruby reds to banana yellows for various applications.

"We not only build protein molecules to send into cells, but we also teach cells to make their own dyes," Tsien said after learning about the Nobel award. "These proteins are trained from birth to be our eyes and ears inside the cells."

The agents are often used in small animal optical imaging for molecular pharmaceutical research and to investigate genetic and proteomic processes associated with cancer. Tumors can be labeled directly with the fluorescent reporter genes. Their optical signature is used to assess tumor burden and micrometastatic tumor growth. In basic research, they are used to measure protein-to-protein interactions and to observe protein migration within cells.

Contag, an associate professor of pediatrics, radiology, and microbiology at Stanford University, developed in vivo optical imaging techniques based on genetically engineered small animals and Tsien's fluorescing dyes. The combination of the three technologies has been adopted for cancer-related pharmaceutical and imaging research.

Tsien was a keynote speaker at the 2004 Society for Molecular Imaging meeting in St. Louis in 2004 and has served on SMI advisory boards.

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