- Huntington's disease (HD) is an inherited neurodegenerative disorder affecting thinking as well as motor function.
- Current treatments are only symptomatic and there is no cure for HD.
- Molecular pathology in HD points to defective regulation of chaperone proteins.
- Increasing levels of chaperone proteins enhance levels of healthy neurons and prevent muscle wasting in HD.
Targeting cellular molecules that regulate chaperone protein production might be a possible therapeutic option in Huntington's disease, according to a team of scientists at the Duke University Medical center.
is an inherited neurodegenerative disease marked by progressive cognitive decline and associated with abnormal involuntary movements not under the patient's control.
‘Increasing chaperone protein levels has shown to enhance the number of healthy neurons and prevent muscle wasting commonly observed in Huntington’s disease.’
The disease begins around the third or fourth decade. The disabilities progressively worsen with time and most persons die within 20 years after diagnosis. At presently there is no cure for the disease. Approximately 1 in 10000 persons are known to suffer from the disease in the United States.
Reason for the Study
It has long been known that defective folding of proteins in the cells is responsible for neurodegenerative diseases such as Alzheimer's Disease
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and Huntington's disease.
The research team at Duke Medical Center who embarked upon the study wished to explore the mechanisms that might be leading to the accumulation of such misfolded proteins within the nerve cells, which is responsible for many of the clinical findings in HD.
Normally, physiological repair mechanisms within the cell either fix the misfolded proteins back to their original shape or if the damage is too extensive, initiate mechanisms for their disposal.
"Normally when proteins misfold, the cells have a mechanism to cope," said senior author Dennis Thiele, Ph.D., George Barth Geller Professor in the Department of Pharmacology and Cancer Biology. "These quality control mechanisms can prod the proteins back into their normal three-dimensional shape, or if the damage is too extensive, target them for removal in the cellular garbage disposal. In Huntington's disease, that's not happening."
Details of the Study
Thiele and his research team employed yeast genetics, chemical biology screening, biochemistry, mouse models and stem cells from patients with Huntington's disease to conduct their research.
The focus of their research was the 'chaperone proteins' which as the name suggests are cellular proteins that act as helpmates and urge the misfolded proteins back to their correct shape.
It was found that the levels of these chaperone proteins were very low in patients with Huntington's disease. The reasons or the mechanisms behind the scarcity of the chaperone proteins remains unknown until now.
Possible Reason for the Scarcity of Chaperones in HD
The Duke led team found that the chief regulator of chaperone production namely HFS1 was being destroyed by a chemical called CK2. The resulting low chaperone protein levels contributed to the accumulation of toxic misfolded proteins. This resulted in the destruction of nerve cells and the characteristic features of HD.
"We demonstrated that we could restore the abundance of the protein chaperones by chemically inhibiting CK2 in a cell model of Huntington's disease, or genetically lowering CK2 kinase levels in a Huntington's disease mouse model," Thiele said. "In both cases, we dramatically increased the number of healthy neurons and we prevented the muscle wasting that is commonly observed in Huntington's disease."
Potential Benefits from the Study
- Drugs that target and possibly reverse or retard the cellular processes that contribute to destruction of neurons leading to signs and symptoms of neurodegeneration in HD can be investigated further in future research.
- The role of such drug targets might also be investigated in other neurodegenerative diseases such as Alzheimer's, Parkinson's and similar diseases.
However, further preclinical research is necessary to know more about the chemicals involved and to outline the precise cellular processes involved.
"We have identified a potential new target for a drug intervention in Huntington's disease," Thiele said, "but there are a lot of basic questions that still need to be answered."
- Huntington's disease - (http://www.mayoclinic.org/diseases-conditions/huntingtons-disease/basics/definition/con-20030685)