Neuronal degeneration, in particular in the striatum, and formation of nuclear and cytoplasmic inclusions are characteristics in Huntington’s disease (HD) that is caused by expansion of a polyglutamine tract located close to the N-terminus of huntingtin (htt). Due to the large (10kb) size of the htt cDNA expression of full-length htt in primary neurons has been difficult in the past.
We generated a new chronic in vitro model that is based on high-capacity adenovirus (HC-Ad) vector-mediated transduction of primary murine striatal and cortical neurons. Since the vector has a large capacity for transport of foreign DNA, it was possible to quantitatively express in these primary cells normal and mutant full-length htt (designed as fusion proteins with EGFP) in addition to its truncated versions. Pathological changes caused by mutant huntingtin were characterized.
The model mimicked several features observed in HD patients: prominent nuclear inclusions in cortical but not in striatal neurons, preferential neuronal degeneration of striatal neurons and neurofilament fragmentation in this cell type. Compared with expressed truncated mutant htt, expression of full-length mutant htt in neurons resulted in a much slower appearance of pathological changes. Different from cortical neurons, the vast majority of nuclei in striatal cells contained only diffusely distributed N-terminal htt fragments. Cytoplasmic inclusions in both cell types contained full-length mutant htt.
This model and the adenovirus vectors used will be valuable to study the function of htt and the pathogenesis of HD at molecular and cellular levels in different neuronal cell types. Copyright © 2012 John Wiley & Sons, Ltd.