The Secret Life of Yeast

By Anna Lau, PhD, Athens Science Café

Earlier this year, the US Food and Drug Administration approved a drug, palbociclib, for treatment of advanced breast cancer. Palbociclib works by inhibiting the function of a protein that controls cell division. Cancer cells divide uncontrollably, so this drug stops these cells from multiplying. Palbociclib is what drug developers call a “rationally designed” drug, one that was developed based on knowledge of a biologically active target. How did the drug developers know about these proteins controlling cell division?

Believe it or not, palbociclib owes its origins to discoveries that were made in yeast. That’s right, say hello to Saccharomyces cerevisiae (SAK-a-ro-MY-sees SER-eh-VISS-ee-ay), the budding yeast.

 

S. cerevisiae leads a double-life—like Diana Prince/Wonder Woman. Most people know the budding yeast as a common ingredient in brewing and bread-baking, but they probably don’t know that the budding yeast is a laboratory superhero, an organism studied by countless research laboratories all over the world! Indeed, the budding yeast is an indispensable genetic model organism [1], a species that researchers can easily manipulate in a laboratory setting.

Why do researchers study yeast? After all, the budding yeast bears no resemblance to humans. True, humans look nothing like yeast, but looks are only skin-deep. At the molecular level, humans have a lot of proteins in common with yeast, especially those that carry out really important activities in the cell, like duplicating DNA, making proteins, and, of course, controlling cell division. The initial discovery of these cell-division proteins in yeast led researchers to identify analogous proteins in humans, and this paved the way to the development of targeted drugs, like palbociclib. (By the way, three researchers were awarded the Nobel Prize in Physiology or Medicine in 2001 for their work on yeast cell division.)

Humans and yeast have so much in common, in fact, that hundreds of essential genes in yeast can be replaced all at once with analogous human versions—and the yeast live! [2] That so many human and yeast genes have retained common functions is testament to the power of natural selection to preserve genes of essential function over a period of a billion years of evolution. This so-called “genetic conservation” is what makes the budding yeast (as well as other model organisms, like fruit flies and nematode worms) important in research—because what researchers discover in yeast can often be recapitulated in humans. We learn about ourselves by studying our very, very, very distant “cousins.”

And we’re not done yet learning from our yeasty cousins. Not a one-hit wonder, research in yeast also helped to clarify the function of telomeres, which protect chromosomes from being whittled away with every round of cell division. (Here, too, three researchers shared the Nobel Prize in Physiology or Medicine in 2009; one studied telomeres in yeast, the other two in Tetrahymena, another model organism.) Some cancers are thought to rely on persistent telomere function for their growth, so researchers are now studying how blocking telomere function might affect cancer growth.

Yay for yeast! They’re great! So, what’s the problem? Well, in the US, the vast majority of so-called “basic” research (or as my friend prefers, “foundational” research, because this research forms the foundation for human discoveries) conducted in yeast and other model organisms is funded through federal agencies, namely the National Institutes of Health and the National Science Foundation. But over the last decade, federal funding for these agencies has been declining, or at best flat. This stagnant funding scenario jeopardizes basic/foundational research as a whole, striking both new and established laboratories that depend on federal grant money to conduct their research programs. Moreover, public opinion over time shows a trend toward favoring a decrease in funding for science research.

So the next time you break bread with friends, or talk over a beer or a glass of wine, let them know how wonderful yeast is and why we need scientists to keep on studying it. As Vannevar Bush penned to President Truman in 1945: “Basic research leads to new knowledge. It provides scientific capital. It creates the fund from which the practical applications of knowledge must be drawn…basic research is the pacemaker of technological progress.” Together, we can help keep technology marching forward.

About the Author

AnnaAnna Lau loves everything science, medicine, and art. When she’s not at her day job as a medical writer, she can be found in her kitchen whipping up a sweet treat or outside trying to keep up with her critters. The perfect vacation for Anna would involve a state or national park, a museum, and yummy food.

References

[1] Twyman R. What are ‘model organisms’? Wellcome Trust: The Human Genome. http://genome.wellcome.ac.uk/doc_wtd020803.html. Published August 28, 2002. Accessed May 28, 2015.

[2] Kachroo AH, Laurent JM, Yellman CM, et al. Systematic humanization of yeast genes reveals conserved functions and genetic modularity. Science. 2015;348(6237):921-925.