Overexpression of human wildtype torsinA and human ΔGAG torsinA in a transgenic mouse model causes phenotypic abnormalities K. Grundmann, a, ⁎ B. Reischmann, a G. Vanhoutte, b J. Hübener, a P. Teismann, c T.-K. Hauser, d M. Bonin, a J. Wilbertz, e S. Horn, f H.P. Nguyen, a M. Kuhn, a S. Chanarat, a H. Wolburg, g A. Van der Linden, b and O. Riess a a Department of Medical Genetics, University of Tuebingen, Calwerstr. 7, 72076 Tuebingen, Germany b Bio-Imaging Laboratory, Department of Biomedical Sciences, University of Antwerp, Campus Middelheim, Groenenborgerlaan 171, 2020 Antwerp, Belgium c School of Medical Sciences College of Life Sciences and Medicine University of Aberdeen Institute of Medical Sciences Foresterhill Aberdeen AB25 2ZD, Scotland, UK d Department of Neuroradiology, University of Tuebingen, Hoppe-Seyler-Str.3 7, 72076 Tuebingen, Germany e Karolinska Institutet, Nobels väg 5, Solna, Stockholm, Sweden f Hertie-Institute for Clinical Brain Research, Center for Neurology, University of Tuebingen, Ottfried-Mueller-Str 27, 72076 Tuebingen, Germany g Institute for Pathology, University of Tubingen, Liebermeisterstrasse 8, 72076, Tuebingen, Germany Received 13 February 2007; revised 13 April 2007; accepted 27 April 2007 Available online 18 May 2007 Primary torsion dystonia is an autosomal-dominant inherited move- ment disorder. Most cases are caused by an in-frame deletion (GAG) of the DYT1 gene encoding torsinA. Reduced penetrance and phenotypic variability suggest that alteration of torsinA amino acid sequence is necessary but not sufficient for development of clinical symptoms and that additional factors must contribute to the factual manifestation of the disease. We generated 4 independent transgenic mouse lines, two overexpressing human mutant torsinA and two overexpressing human wildtype torsinA using a strong murine prion protein promoter. Our data provide for the first time in vivo evidence that not only mutant torsinA is detrimental to neuronal cells but that also wildtype torsinA can lead to neuronal dysfunction when overexpressed at high levels. This hypothesis is supported by (i) neuropathological findings, (ii) neuro- chemistry, (iii) behavioral abnormalities and (iv) DTI-MRI analysis. © 2007 Elsevier Inc. All rights reserved. Keywords: Primary torsion dystonia; TorsinA; DYT1; Transgenic mouse model; Nuclear envelope; DTI-MRI Introduction Primary torsion dystonia (DYT1 dystonia) is an autosomal- dominant inherited neurodevelopmental disorder. Most cases are caused by a 3 base pair (GAG) deletion in the coding region of the DYT1 gene (TOR1A), which is up to now the only known mutation responsible for the development of the disease (Ozelius et al., 1997). DYT1 dystonia manifests as abnormal, involuntary twisting movements most likely due to dysfunction of selective CNS motor circuits. Onset of symptoms is usually restricted to a period between 1 and 28 years of age and penetrance is reduced to 30% (Fahn, 1988; Ozelius et al., 1999), thus it is supposed that other genetic or environmental factors beyond the GAG deletion itself must have an impact on the factual manifestation of the disease. The underlying reason for the more common sporadic forms of dytonia is still unknown however there is increasing evidence, especially from recent association studies investigating polymorphisms in the torsinA gene and in regulatory regions (Clarimon et al., 2005; Kamm et al., 2006; Kock et al., 2006), that genetic variability in the expression of wildtype gene might be a risk factor for the sporadic disease (Clarimon et al., 2005). The specific physiological role of torsinA still remains uncertain. It belongs to the AAA+ (ATPase associated with different cellular activities) protein family, and has been shown to be involved in cellular response to stress (Hewett et al., 2003; Kuner et al., 2003), in neurite outgrowth (Ferrari- Toninelli et al., 2004; Hewett et al., 2006), and dopaminergic transmission (Augood et al., 2002, 2003; Torres et al., 2004). Furthermore, it is still unknown how mutant torsinA disrupts to cellular function of neurons and leads to the development of an www.elsevier.com/locate/ynbdi Neurobiology of Disease 27 (2007) 190 – 206 Abbreviations: CNS, central nervous system; DA, dopamine; DAB, diaminobenzidine tetrahydrochloride; DOPAC, 3,4-dihydroxyphenylacetic acid; DTI, diffusion tensor imaging; ER, endoplasmatic reticulum; HVA, homovanillic acid; 5-HIAA, 5-hydroxyindole-3-acetic acid; FA, functional anisotropy; ΔGAG, GAG deletion; GFP, green fluorescent protein; hWT, human wildtype; kDA, kilo Dalton; MW, molecular weight; NE, nuclear envelope; prp, prion protein promoter; PDI, protein disulfide isomerase; ROI, region of interest; WT, wildtype; MAP-2, microtubule associated protein-2; UPC, ubiquitin–protein conjugate. ⁎ Corresponding author. Fax: +497071 29 5228. E-mail address: Kathrin.Grundmann@med.uni-tuebingen.de (K. Grundmann). Available online on ScienceDirect (www.sciencedirect.com). 0969-9961/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.nbd.2007.04.015