Inquiring Minds: Jeffrey D. Singer on the Nobel Prize in medicine

Jeffrey D. Singer studies cell-cycle regulation. An assistant professor in the Department of Molecular Biology, Cell Biology and Biochemistry, Singer explained to the George Street Journal's Scott J. Turner why Leland H. Hartwell, Sir Paul M. Nurse and R. Timothy Hunt, recently received the 2001 Nobel Prize in Physiology or Medicine for their discoveries of key regulators of the cell cycle.

What did these men find?

Working separately, each dissected the mechanisms and steps involved behind how one cell becomes two, and so on. Each had different, yet complimentary contributions, identifying key molecules that regulate the cell cycle in eukaryotic organisms. This order of life forms embraces yeasts, plants and mammals, including humans.

How did they do this?

Hartwell used the genetic system in brewer’s yeast to make mutations and to examine the types of cells that emerged. His discovery was of a specific class of genes that control the cell cycle. Nurse studied another form of yeast, using genetic screening to find a key cell-cycle regulator, called cyclin dependent kinase, or CDK. Using sea urchins, Hunt discovered cyclins, which are proteins that regulate the CDK function in cells.

Can you flesh this out some more?

Sure. Hartwell found a gene that plays a key role in controlling the cell cycle’s first step. He also coined the term "checkpoint," a powerful concept for understanding cell progression. Nurse showed that CDK was highly conserved during evolution and that it powers a cell through a cycle by modifying other proteins chemically. Hunt showed how cyclins are regulated, which is a mechanism important for controlling the cell cycle.

What do the findings mean?

They have influenced science significantly by explaining extremely important regulating events in mammalian development. For cells to divide appropriately, proliferation mechanisms have to be able to be turned on and off, whether we’re talking about the immune system or skin regeneration.

How does this relate to the uncontrolled growth of cells involved with cancer?

This is very relevant to cancer. We know that it is almost always an error in cell cycle progression that leads to cancer. Many tumors have been shown to have unregulated or barely regulated cyclins. In fact, these abnormalities may be a direct cause of certain tumors. Understanding what is behind the errors in the cell cycle that produced cancer can result in intelligent ways of treating the disease.

The research goal of each of these scientists was not related to cancer?

Each of their original goals was to understand cell cycle progression, not human tumors. It turns out that the two are intimately related.