Breeding and Building Molecules for Whole-Animal and Clinical Imaging

Roger Tsien

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Roger Tsien, PhD, will present a state-of-the-art lecture on “Breeding and Building Molecules for Whole-Animal and Clinical Imaging” during the Thursday, October 29, plenary session, which begins at 8 a.m. Renowned for designing and building molecules that gauge signal transduction, Dr. Tsien has revolutionized the fields of cell biology and neurobiology by making it possible to look inside living cells and study the behavior of molecules in real time.

An investigator at the Howard Hughes Medical Institute at the University of California, San Diego (UCSD), Dr. Tsien is also professor of pharmacology at the UCSD School of Medicine and professor of chemistry and biochemistry at UCSD.

Dr. Tsien will address two complementary topics: the use of fluorescent and singlet-oxygen-generating proteins for imaging at nanometer to millimeter resolution in genetically manipulable cells and organisms, and synthetic peptides aimed at clinical imaging and therapy.

Dr. Tsien developed dyes to track levels of cellular calcium—an ion that regulates many physiological processes, including nerve impulses, muscle contractions, and fertilization. By genetically modifying molecules that make jellyfish and corals glow, Dr. Tsien created fluorescent-colored proteins that can track where and when certain genes are expressed in cells or in whole organisms. Scientists worldwide have used these multicolored fluorescent proteins to study biological processes from the most basic to the most complex.

Over the years, Dr. Tsien has expanded the color palette of fluorescent proteins. He also developed a method to monitor the interactions of two proteins, each labeled with different hues of fluorescent proteins.

Because fluorescent proteins usually require introduction of foreign genes—an action difficult to justify in clinical practice—Dr. Tsien has developed novel, nongenetic ways to image and one day even treat cancer by delivering targeted drugs to tumors. Recently, he and his colleagues built U-shaped peptide molecules to carry an imaging molecule or chemotherapy drug to a tumor. The peptides are substrates for certain proteases—protein-splitting enzymes—that are exuded from tumor cells but rarely seen on normal cells. When the protease splits the bottom of the U, the two arms of the U are separated, unleashing one arm to drag the imaging or drug portion of the peptide into a neighboring cancer cell.

Dr. Tsien was awarded the Nobel Prize in Chemistry in 2008 (shared with Dr. Osamu Shimomura and Dr. Martin Chalfie) for the discovery and development of the green fluorescent protein. He received the Gairdner Foundation International Award in 1995 and the Wolf Prize in Medicine in 2004 for his contribution to the design and application of novel fluorescent and photolabile molecules to analyze and perturb cell signal transduction. He co-founded two bioscience companies; is a member of the National Academy of Sciences, the Royal Society, and the Institute of Medicine; and has published countless scientific papers.

Dr. Tsien received his PhD in physiology from the University of Cambridge in 1977 and remained there to complete his Research Fellowship in 1981.