From greatest to yeast

The human genome may be the latest genetic breakthrough, but the one Biology Assistant Prof. Julie Anderson is studying may also hold a few of life's secrets.

By David Van Meter

The human genetic code, or genome sequence, is not exactly light reading.

The letters A, T, C and G are repeated in varying order enough times to fill 200 phone books. But for Julie Anderson, it's a runaway best seller.

A molecular biologist in her third year at TCU after four years of post-doctoral work at the University of Colorado Health Sciences Center, Anderson has long been interested in how cells divide and die -- or more specifically, the genes that regulate the cellular life cycle. To know how those genes work, Anderson believes, is to figure out how the worst injuries can be reversed, and the cruelest diseases stopped.

"Certain cells divide a lot, like skin cells," explained Anderson from her fifth-floor Winton-Scott lab. "Certain cells in adults don't divide at all, like nerve cells. In the case of spinal cord injuries, damaged nerve cells don't regenerate, and that leads to permanent paralysis.

The more we learn about the life cycle of these cells, the closer we are to one day reversing this paralysis. "In Alzheimer's disease, we know that certain cells in the brain die. Finding out how the life of those cells is regulated and why they are dying is very important in treating that disease."

Yet, to learn why cellular life cycles go awry, Anderson is looking not at the bloated human DNA code, but instead at the double helix sequence of a much simpler life form called Saccharomyces cerevisiae. Or yeast.

Scientists first sequenced its genome in 1996, which has since been followed by the fruit fly and a worm called a nematode. In yeast, approximately 38 percent of its proteins are similar to human proteins.

"In my junior and senior classes, I always try to get across the point to students that genes are responsible for making proteins, and proteins are the workers in our cells," Anderson said.

Currently, Anderson and graduate student Sylvia Zuber are studying a gene that "codes" a protein that ensures every cell's chromosomes are equally divided as the cell prepares to split into two new ones.

"The normal form of the gene (called BUB by scientists, or budding uninhibited in the presence of benomyl) will sense the problem and prevent the cell from dividing," she explains, "but in a cell with a defective gene, the cell doesn't realize its chromosome count is off and it splits, producing cells with too many or two few chromosomes. A hallmark of many tumor cells is that they have a weird number of chromosomes."

Anderson believes that what she learns from yeast can be applied to humans -- which makes the value of the human genome sequence all the more valuable.

"The sequence of the human genome is a high resolution map that gives us a better handle on where problems or mutations are in our genes," Anderson said. "What we can do now -- and this is where computers are extremely valuable -- is take those sequences and compare them with the sequences of other organisms. The thought is that those parts of the genome that are highly conserved throughout evolution all the way from the yeast to the human must have a very important function in how life processes work.

"It really is the frontier of medicine. We're not going to have cures for cancer in two years, but the human genome sequence does allow researchers to move past the laborious sequencing step right into the functional aspect of figuring out how our genes work."