Green tea slows down plaque formation in Huntington's disease

Green tea can apparently inhibit the formation of the lethal protein aggregates that are a characteristic feature of Huntington's disease (HD).

This finding was reported by Dagmar E. Ehrnhoefer, a member of the research group of Dr. Erich Wanker of the Max Delbrück Center for Molecular Medicine Berlin-Buch (MDC), Germany, at the international conference "Neurodegenerative Diseases: Molecular Mechanisms in a Functional Genomics Framework" in Berlin.

She was able to show in an in vitro experiment that the substance epigallocatechin-3-gallate (EGCG), extracted from green tea, interferes with very early events in the aggregation process of the mutant huntingtin protein. Cytoxicity is also reduced.

Moreover, the mobile function of transgenic flies carrying the Huntington's gene improved when they were fed the green tea substance.

The journal Human Molecular Genetics has now published these research findings (Vol. 15, Nr. 18, 15. September 2006, pp. 2743-2751; advanced online access on August 7, 2006).

Dr. Wanker, who is also a professor at the Charité – Universitätsmedizin Berlin, and his colleagues hope that these findings can be a starting point for the development of a medical treatment for Huntington's disease and related diseases.

Huntington's disease, along with Alzheimer's and Parkinson's, belong to the family of neurodegenerative diseases caused by protein misfolding.

Jerky, uncontrolled movements, an unsteady gait and grimaces have given Huntington's disease (HD) its original common name that is still in use today: Huntington's chorea (Old Greek for "dance").

"Huntington's" in the name goes back to the American doctor George Huntington, who became the first to publish a detailed description of the disease in 1872.

The incurable disease is hereditary and has a prevalence of 1 in every 15,000 persons. In Germany, about 8,000 cases are currently known whereas in the US, 30,000 people have HD.

If a child inherits a mutated Huntington's gene from one affected parent, the disease inevitably develops, usually between the ages of 30 and 50. As a result, the nerve cells progressively degenerate in the areas of the brain that control movement and that are involved in memory and emotions. Ten to 30 years after the onset of the disease, Huntington's chorea leads to death.

In 1993, scientists discovered the gene that encodes the protein huntingtin. A mutation in this protein causes the disease and results in the aggregation of the mutant huntingtin protein within the cell nuclei of brain neurons.

In 1997, Dr. Wanker was able to demonstrate that these deposits or aggregates consist of misfolded huntingtin molecules. In the protein factories of the nerve cells of people with Huntington's disease, too many glutamine building blocks have been inserted into the amino acid sequence of huntingtin.

Due to the elongated polyglutamine chains which are formed, the protein loses its normal structure and can no longer be disposed of. Scientists hypothesize that these protein aggregates are toxic to nerve cells.

According to the findings of Dagmar Ehrnhoefer and Dr. Wanker, however, the substance epigallocatechin-3-gallate (EGCG) extracted from green tea slows down this aggregation process.

The research group hopes that these findings will be the starting point for developing a novel drug treatment for HD and related diseases in which misfolded proteins occur.

At the four-day conference, which began in Berlin-Buch on September 6th, around 200 genome researchers and clinicians from Canada, Europe, Japan, and the US discuss the latest findings on neurodegenerative diseases achieved with the aid of gene and protein research.

The organizers of the conference under the umbrella of the National Genome Research Network (NGFN), which is sponsored by the German Federal Ministry for Education and Research, were the MDC, the Charité – University Medical School, and the University of Bonn.