Dysregulation of huntingtin interacting protein networks in human juvenile Huntington's disease brain

BackgroundHuman Huntington's disease (HD) is a genetic neurodegenerative disorder caused by the mutant HTT gene containing CAG repeat expansions, resulting in motor dysfunction and behavioral deficits. CAG repeats of 40-53 occur in adult HD and 60-120 repeats occur in early onset juvenile HD, differing from the normal range of 5-35 repeats.ObjectiveThe HTT gene is translated to the huntingtin (HTT) protein that interacts with proteins in the development of HD. There have been few studies of HTT protein interactors in human HD brain. Therefore, this study evaluated the hypothesis that dysregulation of HTT protein interactors occurs in human juvenile HD brains.MethodsThe strategy of this study was to analyze proteomic data of human juvenile HD brain putamen and cortex regions for dysregulation of HTT interacting proteins, using a database that we compiled of HTT interactors identified in HD model systems from yeast to HD mice.ResultsResults showed significant dysregulation of HTT protein interactors of mitochondria, signal transduction, RNA splicing, chromatin organization, translation, membrane trafficking, endocytosis, vesicle, protein modification, granule membrane, and macroautophagy pathways. The majority of downregulated and upregulated HTT interactors occurred in the putamen region compared to cortex. Dysregulation displayed downregulation of mitochondria and signal transduction interactors, combined with upregulation of RNA splicing, chromatin organization, and translational interactors. Network analysis revealed interactions among clusters of HTT interactors.ConclusionsThese findings demonstrate prevalent dysregulation of HTT protein interactors in human juvenile HD brain, especially in the putamen region that controls movement deficits in HD.