"I had absolutely no role models because there weren't any. I never saw a woman faculty member in science after I graduated from a girl's high school."
Scientist Joan Steitz

As an undergraduate student in the 1960s, Joan Steitz loved science — but she never imagined going into the field, let alone becoming one of the top scientists in the United States.

At that time, there were no women on science faculties at any university, she said.
"It didn't even cross my mind that it was something I would want to do because it just wasn't done. I had absolutely no role models because there weren't any. I never saw a woman faculty member in science after I graduated from a girl's high school."

So Steitz decided to go into medicine because she knew a couple of female physicians and concluded that was something women could do.

Fortunately, the summer before medical school, she got a job working in a lab with cell biologist Joseph Gall, who gave her a project to pursue on her own.

"All of a sudden I got completely turned on," she said. "I decided even if I wasn't ever going to be able to do this like all the men professors I'd known, that this was what I wanted to do, pursue science. It really, really got me and I couldn't believe how much fun it was making discoveries."

On Wednesday, Steitz, now a researcher at the Howard Hughes Medical Institute and the Boyer Center for Molecular Medicine at Yale University, will be announced as one of five winners of this year's Gairdner International Awards, one of the most prestigious prizes in all of science.

Sixty-five of the 279 Gairdner winners have gone on to win the Nobel Prize since the awards were introduced in 1959 by the foundation set up by Toronto businessman James Gairdner.

"Dr. Steitz is one of the most distinguished molecular biologists of her time and has been an outstanding role model to scientists and students everywhere," said Dr. John Dirks, president of the Gairdner Foundation. "I count her as a personal hero in her field."

Steitz, 65, is being honoured for her pioneering work in RNA, a field she began pursuing at Harvard as the sole female graduate student in biochemistry and molecular biology.

Scientists discovered in 1977 that pre-messenger RNA contains stretches of nonsense called introns that interrupt the coding parts of genes.

Everybody knew something strange was going on but nobody had figured it out or predicted it," she recalled. "Finally, evidence began coming in from all over the world and scientists said `wow, that's what's going on.' We have these big segments of junk in the middle of our genes."

That nonsense has to get removed in order to make messenger RNA that codes for proteins in cells, she said.

"Then the question was `how do you get this junk out?' Cells have to have a mechanism for removing the junk to make a message you can read in linear sequence according to the genetic code and make a protein.

"What cellular machinery is there to do that? What it has to do is recognize the boundaries between the junk and the good stuff very precisely and somehow enable the cell to clip out the junk, throw it out and put back together the good bits to be made into protein."

What Steitz discovered was that these little snRNP particles recognize those boundaries, cut out the junk and put the good parts back together.

Part of the reason the discovery was so important, she said, was that it explained how humans are able to have only about five times more genes than bacteria do.

The discovery came about by an unusual marriage of science and medicine. In autoimmune diseases like lupus, people make antibodies against their own cellular components and against these snRNPs. Steitz took antibodies from these patients to discover what was in snRNPs and about how they work. Now, they are being used in reverse for diagnosis and prognosis of those diseases, although no treatment has yet been found.

That falls into another realm of scientific exploration, cellular immunology, "which I firmly believe is where treatments for these problems are going to come from in future," she said.

The discovery ties into cancer research as well because defects in the splicing process give rise to cells making proteins that aren't quite right, which can lead to the uncontrolled growth of cells that is central to cancer.

"So it's basic to all sorts of diseases," she said. "In about 15 to 20 per cent of human disease genes, the mutations affect the splicing of a particular message that makes an important protein for one process or another. What's gone wrong is that the splicing doesn't work because of a mutation in the boundaries between the junk and the sense stuff so snRNPs don't recognize it properly."

Steitz runs a lab of more than 20 people, including 16 graduate and undergraduate students and, in the summer, even high school students. She makes sure all of them are in charge of their own projects, "even if it's very simple, to get them hooked on how much fun it is. It's very valuable for the future and for getting women into science."

She's also involved internationally in projects aimed at removing the barriers and hidden biases that keep women out of the scientific field.

She's married to another Howard Hughes Medical Institute investigator, Thomas Steitz, a professor of biophysics and biochemistry at Yale, whom she met while both were students at Harvard. They have one son who majored in science at Yale, played baseball for the Milwaukee Brewers for three years and now has veered off to Yale Law School.