Magazine article Science News

Unveiling the Tau of Neurodegeneration

Magazine article Science News

Unveiling the Tau of Neurodegeneration

Article excerpt

A protein called tau maintains the structure and function of neurons, the basic cells of the brain and nervous system. Scientists have long thought that disaster would strike anyone whose tau was disrupted. This month, proof arrives that they are right.

Three new studies show that mutations in the gene that encodes the tau protein underlie some forms of frontotemporal dementia (FTD). Though less common than Alzheimer's disease, FTD is one of the most prevalent forms of dementia, accounting for 5 to 10 percent of cases.

In people carrying any of these newly described mutations, neurological degeneration sets in sometime after age 48, the researchers report. Those suffering from the resulting dementia can exhibit diminished speech, tremors similar to those seen in Parkinson's disease, and behavior that resembles schizophrenia.

"Possibly this breakthrough in tau will lead to better understanding of the protein and how it contributes to the death of nerve cells," says Marcelle Morrison-Bogorad, an associate director of the National Institute on Aging in Bethesda, Md. "It's the first time tau has been fingered as the culprit in any genetic disease. It's a protein that's been left out in the cold too long."

Nonetheless, tau is no stranger to neuroscientists. This protein maintains the structure of microtubules, intracellular proteins that act as miniature train tracks within neurons. Microtubules; usher nutrients and other substances back and forth to keep the cell alive and running smoothly.

The tau protein appears to function much like railroad ties, binding the microtubule tracks together and making the trains run on time, Morrison-Bogorad says. The microtubules are then able to deliver goods to the all-important ends of the neuron's long, filamentous structures that can carry signals along nerve channels to distant parts of the body.

If the gene encoding tau has a mutation this system can be disrupted and the neuron dies, three research teams find.

It could be that the proteins produced by the mutated gene don't keep the microtubules together, says neurobiologist Michael Hutton of the Mayo Clinic in Jacksonville, Fla., who coauthored one of the reports. Or, he suggests, the mutations may leave tau protein with nothing to do, and its accumulations may somehow lead to cell death. …

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