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USF professor making strides in cancer research
[12.18.2012]

TAMPA, Fla. – At the University of South Florida, one of the top research universities in the country, important work is being done on mutations in the BLM gene, which lead to a disorder called Bloom Syndrome.

Kristina H. Schmidt, an associate professor in the Department of Cell Biology, Microbiology and Molecular Biology, is a principal investigator and director of the BLM gene research.

Schmidt and her team may have found new types of BLM gene mutations that are too weak to cause Bloom Syndrome, but still may predispose people to cancer and other disorders. Their findings have been published in the Proceedings of the National Academy of Sciences.

The BLM gene, which codes for an enzyme that unwinds the two strands of a duplex DNA molecule, is vital in maintaining stability in most DNA processes. The mutations in the BLM gene associated with Bloom Syndrome inactivate the protein's unwinding activity or nullify protein altogether.

This disorder inhibits the body’s ability to keep its chromosomes correctly structured, which causes instability and disruption in the way other genes function, potentially causing cancer and other complications in humans at a young age.

Schmidt and her team have been conducting their NIH-funded research since 2008. They have been developing model systems using Brewer’s yeast, a single-celled organism whose DNA metabolic pathways are similar to those in human cells, to rapidly evaluate human gene function and collect information quickly.

“We take the yeast model and humanize it by expressing the human BLM gene,” Schmidt said. “Then we place mutations in the gene to test their functionality. The mutations we investigated are among the nearly 100 BLM gene mutations identified in the general population.”

Although most of these mutations had no effect on gene function, they identified six completely inactive alleles (alternate forms of genes) and three partially inactive alleles that impair the BLM gene’s function, but are not currently associated with the disorder.

“The most significant part was that we discovered mutations that had an intermediate effect,” Schmidt said. “Our hypothesis is that if a person has two of these partially active alleles, it will not lead to Bloom Syndrome but the person might have a predisposition to cancer later in life.”

The next step will be to identify the cellular defects of human cells that express these new BLM gene mutations and to identify the underlying biochemical defects of the mutant BLM proteins.

This work is extremely momentous because it begins to address a gap in knowledge that the scientific world currently has about most human genetic disorders: What are the effects of coding polymorphisms and rare DNA sequence variants on the function of disease-associated genes and, thus, on human health?

-USF-



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Author: Sarah Martin
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