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Professor Rhona Borts, during the Frank May lecture which she delivered in 2009.

Yeast, the human genome and infertility

Research in the Department of Genetics is making great insights into the causes of infertility

It is an amazing fact that much of what we know about human genes has actually come from studying common baking or brewers yeast.

Professor Rhona H Borts, Royal Society Wolfson Research Merit Award Holder and Director of the Leicester Institute of Genetics and Genome Science in the University of Leicester’s world-renowned Department of Genetics has been at the forefront of yeast-based research into understanding how organisms reproduce and pass on their DNA.

She was one of the first to appreciate that if human DNA from both parents is not perfectly matched when making a human egg or sperm, then problems such as spontaneous abortion and Down’s syndrome can ensue.

Professor Borts is currently looking at yeast to find new insights into aspects of human health and fertility. In this area, also, she has made the highly exciting suggestion that changes in a gene, already well documented for its link with cancer, might also be involved in male infertility, though in neither case does the existence of the gene mean that either cancer or infertility will result.

One in four or five couples experience infertility, and the vast majority of cases reflect male problems. A number of these may turn out to have a genetic basis, as Professor Borts explained. “All the genes that I’m interested in cause yeast to be infertile and in the last five or ten years laboratory models have indicated that they may be a cause of infertility in men.”

Why has yeast proved so useful in the study of human genetics? “Cells in people, yeast and other organisms all have DNA contained within a nucleus that are the instructions for life. They all must maintain the integrity of this genetic information and pass it on to their offspring,” Professor Borts explained. “Yeast is one of the simplest organisms that can be used to model humans. When we were able to sequence the yeast we found that many genes had exactly the same structure and function as in humans.”

Although yeast is a single cell, it produces two different kinds of cell division: mitosis, making more and more identical copies, rather like human skin cells; and meiosis, involving the process of reducing the duplication of chromosomes after reproduction, as in the human egg or sperm.

A major advantage of working with yeast is that you can experiment on it in ways you can’t with humans. More than that, you can put human genes into yeast and they can function. “If you use human proteins in yeast it could tell you – at some point in the future – whether the human proteins are functioning properly,” Professor Borts said.

Her aim is that in the future better understanding and diagnosis for infertility may allow patients and clinicians to make more informed decisions on treatment options, and may also lead to an earlier diagnosis and prevention of colon cancer.

“I’d like to emphasise the importance of basic research. When I got into this, we didn’t know the genes we were interested in were cancer genes or genes that affected infertility, we just wanted to understand how things worked in the yeast. Now yeast research has opened up whole horizons relating to humans.” Professor Rhona H Borts.

INFORMATION PANEL

Yeast is a single cell with a very small genome. It has about 6,000 genes, whereas humans have 30,000, and it was the first eukaryotic (a cell with a nucleus) to be entirely sequenced.

Professor Rhona Borts has been working with yeast since her post-doctoral years in Boston. After obtaining a Wellcome Trust Senior Fellowship she moved to Oxford to set up her own group working on basic aspects of DNA repair. She was involved in the Pan European project to sequence yeast in the 1990s. After coming to Leicester in 2000 she began looking for ways to translate knowledge gained in yeast to humans and that has led to her work on infertility

Funders for her work include: Cancer Research UK, the Medical Research Council and the Wellcome Trust.