Analysis of Drosophila torp4a for the establishment of a model of early-onset torsion dystonia

NARA I MURARO; KEVIN MOFFAT

Nueva York

Congreso; 10th biennial Neurobiology of Drosophila meeting; 2003

Cold Spring Harbor Laboratory

<p class="MsoBodyTextIndent" style="MARGIN: 0cm 0cm 0pt">Dystonia is a movement disorder characterised by involuntary muscle contractions, frequently causing twisting and repetitive movements or abnormal postures. Early-onset torsion dystonia represents the most severe and common form of hereditary dystonia. A mutation in the DYT1 gene is linked to early-onset torsion dystonia. The protein encoded by the DYT1 gene was named TorsinA. It contains an ATP binding domain and is weakly related to the AAA/HSP/Clp-ATPase superfamily of chaperone-like proteins. In humans and rats, it shows a high level of expression in dopaminergic neurons of the substantia nigra pars compacta, suggesting that TorsinA could be associated with a dysfunction in dopamine transmission. </p>  <p class="MsoBodyTextIndent" style="MARGIN: 0cm 0cm 0pt"><i style="mso-bidi-font-style: normal">Drosophila</i> contains a single homologue of TorsinA, <span style="mso-bidi-font-style: italic">Torp4a</span>, with 34% identity. Its mRNA is found in every developmental stage, including expression in larval and adult brains.</p>  <p class="MsoBodyTextIndent" style="MARGIN: 0cm 0cm 0pt">Transgenic flies overexpressing <i style="mso-bidi-font-style: normal">torp4a</i> have been constructed using the UAS/GAL4 system. Over-expression in the eye causes a rough eye phenotype. An analysis of retinal sections, of these flies, showed a disorganised ommatidial pattern and a significant loss of pigment cells. A screen for enhancers and suppressors of this rough eye phenotype has been performed, and 32 potential genetic interacting loci have been identified, results of the screen will be presented.<span style="mso-spacerun: yes">  </span>Similarly down-regulation of <i>torp4a</i> using the UAS/GAL4 system to drive a double stranded RNAi transgene also caused a rough eye phenotype, the analysis of this phenotype will be shown. </p>  <p class="MsoBodyTextIndent" style="MARGIN: 0cm 0cm 0pt">Finally, a screen to find dominant gain of function alleles of <i>torp4a</i> has been performed using a modified NOVA approach. Seven potential alleles have been isolated, the molecular nature of the deletions is currently being determined</p>  <p class="MsoBodyTextIndent" style="MARGIN: 0cm 0cm 0pt">We conclude that these approaches will allow us to further understand the pathophysiological consequences of Torp4a, and thus TorsinA, dysfunction.</p>