Fall 2011

Molecular Biologist Isolates the TOR Gene in Cells to Find New Cures for Cancer

Dividing S. pombe cells. On the right, photographs of dividing cells are taken using the light microscope. On the left, the same field of cells is being photographed using fluorescent microscope. The nuclei and septa are marked with fluorescent dyes that specifically bind to these cellular structures.
Dr. Ronit Weisman, senior faculty member in the Department of Natural Sciences, has had a special affinity for yeast for the past 15 years. No, she is not a professional baker, nor is she a professional brewer. Dr. Weisman is a molecular biologist who has isolated the TOR gene -- a "master controller" of cell growth and is now on the way to finding more effective treatments for certain types of cancer.

Dr. Weisman, senior faculty member at the Open University's Department of Natural Sciences, possesses a keen mind, passion and extraordinary ability to translate complex subject matter into easy-to-understand concepts. Her lifelong study of TOR -- Target of Rapamaycin -- actually began in Edinburgh about 15 years ago, traveled to Tel Aviv, and continues today at Open University in Ra'anana where she is pursuing her research. In addition to working on the University's molecular biology curriculum, she is devoting her research energy to understanding how to apply the TOR gene to combat specific types of cancer. And, her understanding is growing, thanks to her experimental work with yeast.

Little did Dr. Ronit Weisman suspect that upon leaving Israel 15 years ago to complete her fast track to a doctorate at the University of Edinburgh's world class research center, The Institute of Cell Biology, that she would return to the Open University in Israel. But when she did return, tucked away in her luggage were African-cultivated yeast models, for researching the TOR1 and TOR2 genes and learn more about how they contribute to the body of knowledge on treating cancer in patients. Yeast -- essentially one-cell organisms -- are ideal models for this research.

Why Yeast?

The cell cycle in simple yeast is very similar to the cell cycle in humans. The beauty of working with yeast is that it is relatively easy for researchers to manipulate the gene. "I can analyze genetic interactions -- how one mutated gene interacts with another -- best in yeast models" Dr. Weisman explains.

Researchers have been working with yeast models since the 1960's. Recently two yeast researchers, Dr. Lee Hartwell and Dr. Paul Nurse, were awarded the Nobel Prize for their work on yeast that opened the road to understanding how specific genes control the progress through the cell cycle, and hence control cell divisions. Hartwell chose the yeast Saccharomyces cerevisiae -- the very same yeast that people have been using for thousands of years to brew beer, bake bread and make all sorts of fermented foods and beverages -- as a model because it undergoes easily visualized morphological changes as it progresses through the cell cycle. As it turns out, the same genes that control the cell cycle in baker's yeast (and that malfunction in tumor cells) exist in more or less the same capacity in human cells.

What exactly is TOR?

Upon returning from Edinburgh several years ago, Dr. Weisman 'coincidentally' joined Yigal Kortin's lab at Tel Aviv University where researchers were studying the potential use of a 'new immunosuppressant drug called 'Rapamycin.' Rapamycin binds and inhibits the protein product of the gene TOR, which is an acronym for Target of Rapamycin. At that time, Rapamycin was not yet being used on humans. Soon after, it was used to treat post-transplant patients, where it had some excellent results in inhibiting the proliferation of auto-immune systems.

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