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Heady Discoveries

How yeast is helping scientists learn more about the human body

It is no wonder that yeast is one of the most studied single-celled microorganisms in the world. For thousands of years, it has been used to ferment beer and other alcoholic beverages. Also for thousands of years, yeast has been used to make grains into bread. 

In the last 100 years, scientists realized yeast could be a big help in the battle against disease. It turns out that our cells and yeast cells have a lot in common. For example, they both have a nucleus that houses genetic information. Likewise, the two cells share many of the same genes, which perform many of the same tasks. 

At The University of Texas Graduate School of Biomedical Sciences at Houston, scientists are studying yeast as a model to learn more about how our cells work, what happens when they do not work so well and what might be done to repair malfunctioning cells. 

More than 2,000 scientists have received their training at the graduate school, which is a joint program of The University of Texas Health Science Center at Houston (UTHealth) and The University of Texas MD Anderson Cancer Center

“Yeast is one of the best models for investigations of fundamental processes related to human health,” says Theresa Koehler, PhD, graduate school faculty member and chair of the Department of Microbiology and Molecular Genetics at UTHealth Medical School. “Yeast is easy to grow and easy to manipulate. The well-established genetics of yeast allow microbiologists to alter biological pathways, assessing impact on cell physiology and revealing targets for disease intervention.”

Found on the surface of grapes and other fruits, yeast converts sugars into alcohol. When used in baking recipes, yeast creates the carbon dioxide that causes bread to rise and emits that mouth-watering aroma. 

While there are many species of yeast, baker’s/brewer’s yeast, also known as Saccharomyces cerevisiae, is the yeast of choice in basic science laboratories. Its genome has been decoded by scientists, which makes it easier to compare its genes to those of humans. Yeast mimics many of the biological processes of human cells, including how cells repair themselves when damage occurs from injury or disease. 

“The real power of yeast as an experimental system is that so many people are working on it, generating tools and knowledge,” says Kevin Morano, PhD, a graduate school faculty member and associate professor of microbiology and molecular genetics at UTHealth Medical School. 

Of particular interest to Morano is how the molecules designed to correct cellular damage work. This might yield information that could help people with diseases tied to such damage like Alzheimer’s disease, mad cow disease and Huntington’s disease

The cells’ genetic information encodes molecules called proteins and these proteins need to be folded into specific structures. When misfolding occurs, disease can result. Cells have built-in helpers called “molecular chaperones” to deal with protein misfolding, and Morano’s laboratory is trying to understand how they work. As in life, molecular chaperones guide newly made proteins along their correct paths, and shield them from inappropriate interactions. 

Ambro van Hoof, PhD, one of Morano’s colleagues at the graduate school and an associate professor of microbiology and molecular genetics at UTHealth Medical School, is also using yeast to study how genetic information is regulated. 

The message for making proteins is written in another type of molecule called messenger-RNA. Van Hoof’s laboratory studies how these molecules are broken down after they have performed their function and how that determines how much of each protein gets made. When this process goes wrong in human patients, the wrong proteins get made at the wrong time, which causes either syndromic diarrhea or Perlman syndrome, depending on what exactly goes awry. 

Not limited to studying breakdowns in the transmission of genetic information, yeast models are being used to learn more about how cells respond to viral infections and to find out more about the aging process.

Yeast cells gave researchers the first clues about how a cell works, according to van Hoof. “One of the biggest changes in medicine in the next 10 years will be personalized medicine, where patients get treated because we understand exactly what goes wrong in their cells. This would not be possible without thousands of researchers first figuring out how a yeast cell works,” he says.

Jennifer Herricks, a graduate research assistant, adds, “Yeast is easy to maintain in the laboratory, grow, preserve and manipulate genetically.  Along with the conservation of many molecular mechanisms, this makes yeast an ideal model organism.”

Jennifer Herricks and Tre O’Brien, who are graduate research assistants at The University of Texas Graduate School of Biomedical Sciences at Houston, contributed to the story.

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