Cystamine and cysteamine increase brain levels of BDNF in Huntington disease via HSJ1b and transglutaminase

Huntington disease (HD) is a degenerative brain disease in which brain cells called neurons die as a result of aggregations of the polyQ-huntingtin protein. Symptoms include involuntary movements, personality changes, and dementia, and unfortunately, there is no effective treatment to delay or prevent HD.

In a study appearing April 6 in advance of print publication in the May issue of the Journal of Clinical Investigation, researcher Sandrine Humbert and colleagues at the Institut Curie in France, report that a promising candidate HD drug, cystamine, is able to reduce neuron death and HD symptoms in animals by increasing levels of a protective protein called HSJ1b. The authors found that brains from patients with HD have significantly lower levels of HSJ1b, and that overexpressing HSJ1b in neurons grown in a laboratory dish protects them from polyQ-huntingtin -induced death. Next the researchers created worms that had neuron dysfunction due to the presence of polyQ-huntingtin, and found that the dysfunction could be reduced by HSJ1b.

To identify the mechanism by which cystamine and HSJ1b were protective, the researchers gave cystamine to mice and found that cystamine increased not only levels of HSJ1b, but also levels of BDNF, an important neuron survival factor. These results were confirmed when the authors gave a related, FDA-approved drug, cysteamine, to mice and monkeys with HD. Together these studies reveal that cystamine and cysteamine raise BDNF in an HSJ1b-dependent manner and may be useful as potential treatments for HD.