One of the greatest achievements of modern biology is the remarkable progress that has been made in understanding how genes work. Research by Robert Tjian has contributed substantially to this body of knowledge. Tjian studies the biochemical steps that control the way genes are turned on, and then turned off when their jobs are finished. For nearly 30 years, his research has helped scientists piece together a picture—one that is nearly complete—detailing the molecular machinery used by human cells to "decode" the genome and control the switches that turn genes on and off. This machinery is involved in every facet of human life, including embryogenesis, cellular differentiation, cell growth and development, and the initiation of disease.

Armed with a Ph.D. degree in biochemistry and molecular biology in 1976, Tjian began his scientific career studying how cells live and what happens when cell growth goes awry. At the time, little was understood about how genes are turned on and off. "The field was wide open and promised to be of fundamental importance," recalled Tjian.

Specifically, Tjian studies how genetic information stored in DNA is copied (transcribed) into RNA, which directs the production of proteins inside cells that are essential to life. He has devised a way to isolate the individual components of the cell involved in transcription and recreate this complex, highly regulated process in a test tube. Advances in technology have also enabled Tjian to purify rare sequence-specific transcription factors, which bind to DNA at specific sites and regulate the expression of genes, and to isolate the genes that encode these important transcription factors.

His work has provided new insights into the molecular mechanisms that underlie various human diseases and conditions, including Huntington's disease, cancer, diabetes, and infertility.

Tjian has been actively involved in training a new generation of molecular biologists who are poised to answer new questions generated by today's scientists. "It gives me great pride to have guided so many students into medical careers, and to watch my students and postdoctoral fellows develop into first-rate scientists," said Tjian.

In April 2009, Tjian became president of HHMI. He continues his research on the biochemistry of gene regulation at HHMI's Janelia Farm Research Campus and at the University of California, Berkeley.