ApoptosisWhat do Worm Cells, the Space Between My Fingers, and Cancer Have in Common?
In C. elegans, as well as in nearly all other animals, part of development includes cells undergoing a programmed cell death known as apoptosis. That is, a cell divides by mitosis to produce two daughter cells, one of which continues to function while the other one dies shortly after its birth.
Studies of mutant worms, in which apoptosis did not occur normally, led to the identification of genes responsible for programmed cell death in C. elegans. Figure 2, at right, shows three C. elegans cells (indicated by arrows) that have recently undergone this programmed cell death.
The process is shown more dynamically in a movie from the Goldstein Lab at the University of North Carolina. Again, note how the worm's advantages as a model organism for development, described in the introduction have helped enable these kinds of studies.
Building on the work on the genes for apoptosis in worms, scientists extended the knowledged to other organisms -- including humans. For example, it was later discovered that the webbing of skin found between the digits of a human hand during fetal development is eliminated during later stages of development because of proteins made by these apoptosis genes.
Research on apoptosis in C.elegans has also contributed to our understanding of cancer in humans. Apoptosis is also used to destroy human cells with DNA damage. If apoptosis fails to kill cells with damaged DNA, these cells may continue to divide, and can lead to the development and progression of cancer. An image of a human cell that has undergone apoptosis is shown in Figure 4 at the right.
A Nobel Prize was awarded to Sydney Brenner, John Sulston, and H. Robert Horvitz for their work in developing C. elegans as a model organism, describing the cell lineages, and discovering the molecular basis for apoptosis. [Read more about the Nobel Prize.]