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Effects of ataxins-3 loss and gain of function : characterization of neuronal cell lines overexpressing wild-type and mutant forms of mutant ataxin-3

Year: 2013
Type: dissertation
Abstract: Machado-Joseph Disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant neurodegenerative disorder which involves the cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems. MJD is caused by an expanded CAG repeat in the coding region of the ataxin-3 gene; for this reason it belongs to the group of polyglutamine (polyQ) associated diseases. The normal function of the ataxin-3 protein (ATXN3) remains mostly unknown, although there are some data suggesting a role for this protein in the modulation of protein degradation (either by the UPS or through autophagy) in association with its deubiquitylase (DUB) activity. Other evidence suggests a role in transcription regulation, in the cellular response(s) to stress and in the cytoskeleton organization as well as in cellular adhesion. In this work we studied the normal function of ATXN3 in neurons, using a novel neuroblastoma SH-SY5Y cell-based approach. We characterized all the different cell lines, assessing cell differentiation and survival, morphology, adhesion and cytoskeleton features, in cells overexpressing wild-type (ATXN3_28Q) and expanded (ATXN3_83Q) ATXN3 as well as cells expressing a catalytic mutant version of this protein (ATXN3_C14A). We also evaluated the transcriptomic profile and protein expression of the cell lines and further investigated the pathways underlying the cellular changes and cytoskeletal regulators. Moreover, in cells expressing both mutant and expanded ATXN3, we found a decreased expression of α-5 integrin (ITGA5) and inhibition of its downstream partners’ activity. The findings described in this study led us to hypothesize that the DUB activity of ATXN3 underlie the neuronal phenotype regulation and also that the expansion of the polyQ tract causes partial loss of function.
Language: English
Open Access status: green
OpenAlex ID: W2265657539
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