Scientists have made a novel discovery in the fight against Huntington’s disease (HD).
HD is an incurable progressive neurodegenerative genetic disorder which affects motor coordination and leads to cognitive decline and dementia.
The disease pathology stems from a mutation in the huntingtin (Htt) gene, which results in the accumulation of toxic proteins leading to neuronal cell death.
Previous studies have clearly implicated caspases – enzymes that break down cells – as key players in the cascade of events involved in HD neuronal death.
Now scientists have identified three small molecules that inhibit the activity of those caspases, suppressing toxicity and rescuing neurons from cell death in cell culture.
The research was led by both Buck Institute faculty member Lisa Ellerby, and Yale University faculty member Jonathan Ellman. Dr. Ellerby is doing follow up studies in a mouse model of the disease.
Dr. Ellerby said a substrate based screening method was used to identify compounds that reacted with caspases. Based on those reactions, Jonathan Ellman, from the Yale University Department of Chemistry, converted the compounds to caspase inhibitors.
Dr. Ellerby said that the inhibitors are based on properties of a drug, which had entered Phase I clinical trials for the treatment of human liver preservation injury.
“These molecules shows particular promise. They cross the blood-brain barrier and acts selectively to block the processes involved in HD,” said Ellerby.
Dr. Ellerby said the caspase inhibitors both suppressed the proteolysis of Htt and rescued HD neurons that have begun to undergo cell death.
“We believe this is going to help us move the field forward because now we can test these compounds in live animals. Up until this point we have not identified a caspase inhibitor that has acted selectively against the toxic effects of the Htt mutation,” said Dr. Ellerby.