Horvitz, H. Robert

Horvitz, H. Robert, born in 1947, American geneticist and cowinner of the 2002 Nobel Prize in physiology or medicine for his discoveries concerning the genetic regulation of programmed cell death, the process in which healthy cells kill themselves as a normal part of an organism’s development. Horvitz shared the prize with two former colleagues, British geneticists Sydney Brenner and Sir John E. Sulston.

Horvitz was born in Chicago, Illinois. He received his undergraduate degree in mathematics and economics from the Massachusetts Institute of Technology (MIT) in 1968. In 1974 he earned a doctoral degree in biology from Harvard University. While at Harvard he worked in the laboratories of two Nobel laureates, biochemist James D. Watson and molecular biologist Walter Gilbert.

In 1974 Horvitz joined the laboratory of Sydney Brenner at the Medical Research Council (MRC) in Cambridge, England, where Sulston was also working. There Horvitz performed postgraduate research on the roundworm Caenorhabditis elegans. This tiny worm, with fewer than 1,000 cells, had been chosen by Brenner to study how genes regulate cell division, cell specialization, and organ development in multicellular animals. Horvitz worked with Sulston to trace the development of each cell in C. elegans as the organism grew from a fertilized egg to an adult. As a result of these studies Sulston discovered that specific cells undergo programmed cell death, also known as apoptosis, as part of the organism’s normal development. Sulston also identified the first mutation of a gene participating in the cell death process.

In 1978 Horvitz became assistant professor of biology at MIT; he was named David H. Koch Professor of Biology there in 1986. At MIT Horvitz pursued the problem of the genetic regulation of cellular development in C. elegans. He and his associates identified 15 genes that play roles in programmed cell death. Some of these genes instruct a cell to kill itself. Other genes direct cells to engulf and digest neighboring cells that die by programmed cell death. Horvitz identified one gene that protects against cell death by interacting with other genes involved in the cell death process. Horvitz also found that corresponding genes regulating programmed cell death exist in humans. These discoveries broadened scientific understanding of a number of human diseases that result when programmed cell death goes awry, including acquired immunodeficiency syndrome (AIDS), coronary heart disease, stroke, and cancer.

In 1988 Horvitz was appointed an investigator of the Howard Hughes Medical Institute, an organization, based in Chevy Chase, Maryland that supports the research of outstanding biomedical scientists at universities around the world. In addition to the Nobel Prize, Horvitz received the Alfred P. Sloan Jr. Prize from the General Motors Cancer Research Foundation in 1998 and the Gairdner Foundation International Award in 1999.