Thursday, November 05, 2009

Nobel Laureate: Lee Hartwell


The Nobel Prize in Physiology or Medicine 2001

"for their discoveries of key regulators of the cell cycle"

Leland H. Hartwell (1939 - ) won the Nobel Prize for his contributions to understanding the cell cycle. His discovery of the regulatory molecule CDC28 led to the idea of "checkpoints"—steps in the cell cycle where specific action is needed to progress to the next stage.

Hartwell shared the 2001 Nobel Prize with Paul Nurse and Tim Hunt.

Some of you may think that elucidation of the cell cycle in yeast isn't such a big deal. You would be wrong. No only did this work stimulate a huge field of study in yeast, but the genes and the pathways uncovered in yeast are similar to those in other eukaryotic cells. This is a case where fundamental basic science has lead to a deep understanding of how life works at the molecular level.

Nobel Laureates
I already posted the press release under Nobel Laureate: Sir Paul Nurse. It's a very good description of the work that was done by all three Nobel Laureates.

Here's an excerpt from the Presentation Speech.

This year's Nobel Laureates have discovered the key regulators of the cell cycle, cyclin dependent kinase (CDK) and cyclin. Together these two components form an enzyme, in which CDK is comparable to a "molecular engine" that drives the cell through the cell cycle by altering the structure and function of other proteins in the cell. Cyclin is the main switch that turns the "CDK engine" on and off. This cell cycle engine operates in the same way in such widely disparate organisms as yeast cells, plants, animals and humans.

How were the key regulators CDK and cyclin discovered?

Lee Hartwell realized the great potential of genetic methods for cell cycle studies. He chose baker's yeast as a model organism. In the microscope he could identify genetically altered cells - mutated cells - that stopped in the cell cycle when they were cultured at an elevated temperature. Using this method Hartwell discovered, in the early 1970s, dozens of genes specific to the cell division cycle, which he named CDC genes. One of these genes, CDC28, controls the initiation of each cell cycle, the "start" function. Hartwell also formulated the concept of "checkpoints," which ensure that cell cycle events occur in the correct order. Checkpoints are comparable to the program in a washing machine that checks if one step has been properly completed before the next can start. Checkpoint defects are considered to be one of the reasons behind the transformation of normal cells into cancer cells.

[Photo Credit: Susie Fitzhugh and the Fred Hutchinson Cancer Research Center]

The images of the Nobel Prize medals are registered trademarks of the Nobel Foundation (© The Nobel Foundation). They are used here, with permission, for educational purposes only.

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