¹Neuronal Survival Unit, Department of Experimental Medical Science, Wallenberg Neuroscience Center, Lund University, BMC A10, Lund 22184, Sweden

Correspondence: T Zuchner, Neuronal Survival Unit, Department of Experimental Medical Science, Wallenberg Neuroscience Center, Lund University, BMC A10, Lund 22184, Sweden. Tel: +49 341 9731334; Fax: +49 341 9731339; E-mail: Thole.Zuechner@bbz.uni-leipzig.de

²Current address: Ultrasensitive Protein Detection Unit, Center for Biotechnology and Biomedicine, Institute for Bioanalytical Chemistry, University of Leipzig, Deutscher Platz 5, Leipzig 04103, Germany

Received 9 May 2007; Revised 24 September 2007; Accepted 26 September 2007; Published online 2 November 2007.

Abstract

Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a mutation in the gene huntingtin and characterized by motor, cognitive and psychiatric symptoms. Huntingtin contains a CAG repeat in exon 1. An expansion of this CAG repeat above 35 results in misfolding of Huntingtin, giving rise to protein aggregates and neuronal cell death. There are several transgenic HD mouse models that reproduce most of the features of the human disorder, for example protein inclusions, some neurodegeneration as well as motor and cognitive symptoms. At the same time, a subgroup of the HD transgenic mouse models exhibit dramatically reduced susceptibility to excitotoxicity. The mechanism behind this is unknown. Here, we review the literature regarding this phenomenon, attempt to explain what protein domains are crucial for this phenomenon and point toward a putative mechanism. We suggest, that the C-terminal domain of exon 1 Huntingtin, namely the proline rich domain, is responsible for mediating a neuroprotective effect against excitotoxicity. Furthermore, we point out the possible importance of this mechanism for future therapies in neurological disorders that have been suggested to be associated with excitotoxicity, for example Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis.