Tuesday, October 08, 2013
Wisconsin researchers studying the effect of a shortage of zinc in yeast have concluded that a deficiency of the element in humans might have a link to certain illnesses. If their work can be replicated in human subjects, it could suggest a relationship between zinc deficiency and diseases such as Alzheimer's and Parkinson's.
Scientists at the University of Wisconsin-Madison chose yeast for their initial study because of the simplicity of the organism, according to ScienceDaily. It's a single-celled fungus, yet has distinct similarities to human cells. It can adapt to both zinc excesses and shortages. The researchers published their findings in the Journal of Biological Chemistry.
The team already knew that proteins stop functioning and clump when damaged by chemicals or high temperatures. The resulting clumps are classic signatures of Alzheimer's disease and Parkinson's disease. Their study showed that a shortage of zinc is also a stressor that can cause clumping.
The University of Maryland Medical Center says that zinc is the second-most common mineral found in human cells, ranking behind iron. It plays an important part in wound healing, growth, taste, immunity, vision, smell, reproduction, blood clotting, thyroid function, and insulin activity. However, an overabundance can be toxic.
Alzheimer's disease, the most common form of dementia, affects more than 5 million adults, according to the Alzheimer's Association. Its estimated U.S. price tag for 2013 is $203 billion, a figure expected to increase to $1.2 trillion by the year 2050.
According to the National Institute of Neurological Disorders and Stroke, Parkinson's disease is a motor system disorder that develops as the patient loses brain cells that produce dopamine. It's a progressive illness that typically strikes individuals who are older than 50.
The Wisconsin team found that a gene called Tsa1 produces substances -- guardians of sorts -- that interfere with clumping of proteins in cells. This prevents damage that could advance to cell death. Without enough zinc, an organism doesn't have Tsa1 guardians. The proteins clump and create a process that ultimately kills the cell.
The study results suggest that if the level of zinc in yeast cells has a similar effect on human cells, that could indicate a potential link between a shortage of the element and diseases such as Alzheimer's and Parkinson's. The researchers have noted that a similar Tsa1 system is present in animals. They have indicated that they have plans to study the Tsa1 system in cultures of human cells. Despite similarities between yeast and human cells, for many who read about the research, the gap between the yeast study and a link to these human diseases is a chasm.
Colin W. MacDiarmid, Janet Taggart, Kittikhun Kerdsomboon, Michael Kubisiak, Supawee Panascharoen, Katherine Schelble, and David J. Eide
Peroxiredoxin chaperone activity is critical for protein homeostasis in zinc-deficient yeast
J. Biol. Chem. jbc.M113.512384
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