May 4, 2001

Exton elected to prestigious National Academy of Sciences

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Exton elected to prestigious
National Academy of Sciences

Dr. John H. Exton, professor of Molecular Physiology & Biophysics and Pharmacology, and Howard Hughes Medical Institute investigator, was elected this week to the prestigious National Academy of Sciences.

The Academy, a private non-profit society of scientists and engineers established by the U.S. Congress in 1863, elected 72 American members and 15 foreign associates on May 1 "in recognition of their distinguished and continuing achievements in original research." Election to the Academy is considered one of the highest honors a scientist can achieve.

Exton becomes the fifth Vanderbilt faculty member in the National Academy of Sciences. He joins Stanley Cohen, Ph.D., Distinguished Professor Emeritus of Biochemistry, Dr. William J. Darby, professor emeritus of Biochemistry, Jon H. Kaas, Ph.D., Centennial Professor of Psychology, and Dr. Charles R. “Rollo” Park, professor emeritus of Physiology.

Exton was elected to the NAS for his career-long contributions to the area of signal transduction – how hormones, neurotransmitters, and growth factors ‘talk’ to cells in order to regulate cell functions.

“John has made many seminal observations over the years,” said Alan D. Cherrington, Ph.D., Charles H. Best Professor of Diabetes Research, professor and chair of Molecular Physiology & Biophysics. “He has made major contributions to our understanding of signaling pathways, and this recognition is certainly well-deserved.”

Exton came to Vanderbilt as a postdoctoral fellow to study with Academy member Park and the late Dr. Earl W. Sutherland, 1971 Nobel Laureate in Physiology or Medicine. Together they studied hormone and substrate regulation of sugar metabolism in the liver. Exton’s findings helped explain the changes in liver carbohydrate metabolism seen in starvation and diabetes.

“He was outstanding from the very beginning, and we were fortunate to keep him here on the faculty,” Park said. “He is a very prominent member of the scientific community, and his work has substantially extended our knowledge of basic physiological mechanisms underlying hormone action.”

In extending scientific knowledge, Exton sometimes found himself challenging the accepted version of how things work.

He was among those who first realized that there was more than one way for hormones to send a signal across the cell membrane. At the time, the single accepted signaling pathway involved the messenger molecule cyclic AMP. Exton and others found another pathway at work that included the action of an enzyme called phospholipase C that breaks down lipids (fat molecules) in the cell membrane.

He went on to participate in the identification of a key molecular member of this second signaling pathway: the G protein Gq.

“The discovery of Gq came about because of an amazing constellation of research by three labs. We all got part of the picture, and it was an incredible bit of scientific collaboration,” Exton said.

Exton bumped up against accepted models again when he realized that phospholipase C wasn’t the only enzyme breaking down lipids in the cell membrane. His data led to the discovery that the enzyme phospholipase D was also at work in a second lipid signaling pathway.

“I haven’t deliberately gone against conventional understanding,” Exton said. “I just find what I find. I have confidence in my data, so I don’t hesitate to challenge dogma.”

His laboratory currently focuses on the ‘Rho’ family of small GTP-binding proteins, which are important participants in signaling pathways regulating cell growth, shape, and movement.

Exton attributes his confidence and willingness to challenge scientific dogma to excellent scientific training since the beginning: as a medical student at the University of New Zealand, as a graduate student at the University of Otago, New Zealand, and as a postdoctoral fellow and young faculty member at Vanderbilt.

Exton adds his election to the NAS to a long list of honors including the Lilly Award from the American Diabetes Association, a Doctor Honoris Causa from the Autonomous University of Barcelona, the Drummond Award from the University of Calgary, the Vanderbilt Sutherland Award, and the VUMC Stanley Cohen Award. He is also a Fellow of the American Association for the Advancement of Science, a University National Scholar, New Zealand and a Commonwealth Scholar, United Kingdom.