Andreia Alexandra Neves Carvalho - ICVS, University of Minho
Title: ATXN3 modulates mRNA splicing of Tau through ubiquitylation of splicing factors
Abstract:
Deubiquitylating (DUB) enzymes have been recognized as central players in the maintenance of the correct ubiquitylation/deubiquitylation balance in cells. Ataxin-3 (ATXN3) is a protein with DUB activity mutated in Machado-Joseph disease (MJD) (also known as Spinocerebellar ataxia type 3 – SCA3). To date, besides the involvement of ATXN3 in the Ubiquitin-proteasome pathway (UPP) its physiological function remain elusive and no substrates for its DUB activity have been identified. To identify potential candidates of the DUB activity of this protein, we characterized the ubiquitome of neuronal cells lacking ATXN3 (ATXN3shRNA cells) by mass-spectrometry. We found that a large proportion of the proteins with altered polyubiquitylation in ATXN3shRNA cells were proteins involved in RNA post-transcriptional modification. By transcriptomic analysis and using reporter minigenes we confirmed that splicing was globally altered in cells lacking ATXN3. Among the targets with altered splicing was SRSF7(9G8), a regulator of tau exon 10 splicing. Here we show that loss of function of ATXN3 leads to a deregulation of tau exon 10 splicing resulting in a decreased 4R/3R tau ratio. The fact that similar alterations were found in the brain of a mouse model of MJD, suggests that this mechanism might be contributing for the pathogenesis of MJD, and establishes a link between two key proteins involved in different neurodegenerative disorders.
Title: ATXN3 modulates mRNA splicing of Tau through ubiquitylation of splicing factors
Abstract:
Deubiquitylating (DUB) enzymes have been recognized as central players in the maintenance of the correct ubiquitylation/deubiquitylation balance in cells. Ataxin-3 (ATXN3) is a protein with DUB activity mutated in Machado-Joseph disease (MJD) (also known as Spinocerebellar ataxia type 3 – SCA3). To date, besides the involvement of ATXN3 in the Ubiquitin-proteasome pathway (UPP) its physiological function remain elusive and no substrates for its DUB activity have been identified. To identify potential candidates of the DUB activity of this protein, we characterized the ubiquitome of neuronal cells lacking ATXN3 (ATXN3shRNA cells) by mass-spectrometry. We found that a large proportion of the proteins with altered polyubiquitylation in ATXN3shRNA cells were proteins involved in RNA post-transcriptional modification. By transcriptomic analysis and using reporter minigenes we confirmed that splicing was globally altered in cells lacking ATXN3. Among the targets with altered splicing was SRSF7(9G8), a regulator of tau exon 10 splicing. Here we show that loss of function of ATXN3 leads to a deregulation of tau exon 10 splicing resulting in a decreased 4R/3R tau ratio. The fact that similar alterations were found in the brain of a mouse model of MJD, suggests that this mechanism might be contributing for the pathogenesis of MJD, and establishes a link between two key proteins involved in different neurodegenerative disorders.