Worms Expose How to Destroy Toxic Cells in Huntington’s Disease
Neurodegenerative diseases are a specific class of diseases characterized by a slow, progressive deterioration of nerve cells and the body processes they control. One of the most devastating neurodegenerative diseases, Huntington’s, is caused by mutations of the huntingtin gene inherited on the short arm of chromosome 4. The mutations cause continuous repeats of the nucleotide building blocks that contain the gene’s instructions and—along with proteins aggregating near neurons—lead to nerve degeneration.
Nerve degeneration causes damage to the areas of the brain that regulate physical movement and conscious thought. In particular, Huntington’s disease patients experience uncontrollable muscle movements known as chorea, loss of coordination, deteriorating memory, impaired speech, and even personality changes. Currently, over 30,000 people in the United States have Huntington’s disease, and about 200,000 more are at risk—making research into the internal mechanisms that cause the associated symptoms more critical than ever.
Fortunately, insights from a recent study by researchers at the Monash Biomedicine Discovery Institute and the University of Cambridge in the United Kingdom have helped identify a potential pathway to eliminating one of the suspected contributors to Huntington’s disease. The study focuses on microRNAs —short pieces of genetic material that regulate multiple genes simultaneously. During the study, researchers were interested in the microRNAs that regulate the expression of the protein aggregates thought to trigger neurodegeneration.
Scientists found that the microRNA miR-1 is found at very low levels in patients with neurodegenerative diseases. Fortunately, miR-1 is also found in the same sequence in an ancient worm—Caenorhabditis elegans—that evolved over 600 million years ago. Studying the effects of miR-1 in worms is much easier than studying it in humans.
MicroRNA May Help Protect Against Aggregation
During the research, when miR-1 was eliminated in the worm and applied to a lab model of Huntington’s disease, more protein aggregation occurred. miR-1 appears to control the expression of the TCB-7 protein in worms, which regulates autophagy. Through autophagy, the body removes or recycles damaged cells—including the damaged protein cells that accumulate and form toxic aggregates in neurons.
A lack of miR-1 inhibits the autophagy process, resulting in Huntington’s protein aggregation in the worms. Further investigations were able to isolate an autophagy pathway in humans controlled by the same microRNA, suggesting that manipulation of miR-1 can increase or decrease protein aggregations in humans. By uncovering the benefits of manipulation, researchers were able to validate that increasing miR-1 expression, they could reduce and remove the amount of Huntington’s protein aggregates in human cells.
Implications for the Future
Manipulation of miR-1 could prove a vital way of reducing or eliminating the toxic Huntington’s protein aggregates that contribute to neurodegeneration, loss of muscle control, and dementia. Further research could lead to the development of therapeutic pharmaceuticals that could drastically impact the millions of people with Huntington’s disease and other devastating neurodegenerative diseases very soon.