Dysregulated Striatal Neuronal Processing and Impaired Motor Behavior in Mice Lacking Huntingtin Interacting Protein 14 (HIP14)

Palmitoyl acyl transferases (PATs) play a critical role in protein trafficking and function. Huntingtin interacting protein 14 (HIP14) is a PAT that acts on proteins associated with neuronal transmission, suggesting that deficient protein palmitoylation by HIP14, which occurs in the YAC128 model of Huntington's disease (HD), might have deleterious effects on neurobehavioral processing. HIP14 knockout mice show biochemical and neuropathological changes in the striatum, a forebrain region affected by HD that guides behavioral choice and motor flexibility. Thus, we evaluated the performance of these mice in two tests of motor ability: nest-building and plus maze turning behavior. Relative to wild-type controls, HIP14 knockout mice show impaired nest building and decreased turning in the plus maze. When we recorded the activity of striatal neurons during plus-maze performance, we found faster firing rates and dysregulated spike bursting in HIP14 knockouts compared to wild-type. There was also less correlated firing between simultaneously recorded neuronal pairs in the HIP14 knockouts. Overall, our results indicate that HIP14 is critically involved in behavioral modulation of striatal processing. In the absence of HIP14, striatal neurons become dysfunctional, leading to impaired motor behavior.