Deciphering Syne1 isoforms contribution to Autosomal Recessive Cerebellar Ataxia type 1 (ARCA1)

Objectives Several SYNE1/Msp-300 isoforms have been identified and it is thought that they present a tissue specific expression pattern (Rajgor et al., 2012). The project aims first at identifying neuronal Msp-300 isoforms and the neuron population in which Msp-300 function is required. The different isoforms will be knocked-down by combining RNAi and Gal4/UAS approaches. Six UAS-RNAi lines targeting different Msp-300 isoforms subsets have been generated by the Vienna Consortium. We previously successfully used the UAS-exon32(RNAi) line together with a muscle specific Gal4 to mimic Msp-300∆KASH (Morel et al., 2014). The student will first subject flies expressing the UAS-RNAi lines with a pan-neural Gal4 driver to climbing assays. They will be compared to Msp-300∆KASH as a control for ARCA1 model. Identified UAS-RNAi lines will then be combined with neuron specific Gal4 lines to determine the relevant neuron sub-population. Dopaminergic, serotoninergic, cholinergic, Gabaergic and glutamatergic neurons will specifically be targeted. Contribution to neurons function will be assessed by climbing assay. The second aim of the project is to investigate Msp-300 neural isoforms’ cellular function. Since ARCA1 is associated with cerebellar atrophy, the student will particularly investigate a potential effect on neuron survival and neuron morphology. Neural subpopulation or single neurons will be labelled and their neural population size as well as neuron morphology will be investigated by confocal imaging comparing wild-type and RNAi mutant conditions. Finally, depending on project progress, remaining Msp-300 isoforms subcellular localization and synapse organization in the relevant neuron subpopulation will be documented (Urwyler et al., 2015). By identifying Msp-300 isoforms and the relevantneuron sub-populations, this project will give the means todissect SYNE1 contribution to neuron function. As such, itconstitutes a first step toward a molecular and cellularunderstanding of ARCA1. BibliographyCottrell, J.R., Borok, E., Horvath, T.L., and Nedivi, E. (2004). CPG2: abrainand synapse-specific protein that regulates the endocytosis ofglutamate receptors. Neuron 44, 677–690. Dupré, N., Gros-Louis, F., Chrestian, N., Verreault, S., Brunet, D., deVerteuil, D., Brais, B., Bouchard, J.-P., and Rouleau, G.A. (2007). Clinicaland genetic study of autosomal recessive cerebellar ataxia type 1. Ann.Neurol. 62, 93–98. Gros-Louis, F., Dupre, N., Dion, P., Fox, M. A., Laurent, S., Verreault, S.,Sanes, J. R., Bouchard, J. P., and Rouleau, G. A. (2007). Mutations inSYNE1 lead to a newly discovered form of autosomal recessivecerebellar ataxia. Nat Genet 39, 80-85. Morel, V., Lepicard, S., Rey, A.N., Parmentier, M.-L., and Schaeffer, L.(2014). Drosophila Nesprin-1 controls glutamate receptor density atneuromuscular junctions. Cell. Mol. Life Sci. CMLS 71, 3363–3379. Noreau, A., Bourassa, C.V., Szuto, A., Levert, A., Dobrzeniecka, S., Gauthier, J., Forlani, S., Durr, A., Anheim, M., Stevanin, G., et al. (2013).SYNE1 mutations in autosomal recessive cerebellar ataxia. JAMA Neurol. 70, 1296–1231. Rajgor, D., Mellad, J.A., Autore, F., Zhang, Q., and Shanahan, C.M. (2012).Multiple novel nesprin-1 and nesprin-2 variants act as versatile tissue-specific intracellular scaffolds. PloS One 7, e40098. Razafsky, D., and Hodzic, D. (2015). A variant of Nesprin1 giant devoidof KASH domain underlies the molecular etiology of autosomalrecessive cerebellar ataxia type I. Neurobiol. Dis. 78, 57–67. Urwyler, O., Izadifar, A., Dascenco, D., Petrovic, M., He, H., Ayaz, D.,Kremer, A., Lippens, S., Baatsen, P., Guérin, C.J., et al. (2015).Investigating CNS synaptogenesis at single-synapse resolution bycombining reverse genetics with correlative light and electronmicroscopy. Development 142, 394–405. LocationLaboratoire de Biologie Moléculaire de la cellule(LBMC)ENS de Lyon46 Allée d’Italie69007 LyonFranceDuration3 months Language(French/English/Both)Both