The ataxia protein sacsin is a functional co-chaperone that protects against polyglutamine-expanded ataxin-1
- Parfitt, David A, Michael, Gregory J, Vermeulen, Esmeralda G M, Prodromou, Natalia V, Webb, Tom R, Gallo, Jean-Marc, Cheetham, Michael E, Nicoll, William S, Blatch, Gregory L, Chapple, J Paul
- Authors: Parfitt, David A , Michael, Gregory J , Vermeulen, Esmeralda G M , Prodromou, Natalia V , Webb, Tom R , Gallo, Jean-Marc , Cheetham, Michael E , Nicoll, William S , Blatch, Gregory L , Chapple, J Paul
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6485 , http://hdl.handle.net/10962/d1006262 , http://hmg.oxfordjournals.org/content/18/9/1556
- Description: An extensive protein–protein interaction network has been identified between proteins implicated in inherited ataxias. The protein sacsin, which is mutated in the early-onset neurodegenerative disease autosomal recessive spastic ataxia of Charlevoix-Saguenay, is a node in this interactome. Here, we have established the neuronal expression of sacsin and functionally characterized domains of the 4579 amino acid protein. Sacsin is most highly expressed in large neurons, particularly within brain motor systems, including cerebellar Purkinje cells. Its subcellular localization in SH-SY5Y neuroblastoma cells was predominantly cytoplasmic with a mitochondrial component. We identified a putative ubiquitin-like (UbL) domain at the N-terminus of sacsin and demonstrated an interaction with the proteasome. Furthermore, sacsin contains a predicted J-domain, the defining feature of DnaJ/Hsp40 proteins. Using a bacterial complementation assay, the sacsin J-domain was demonstrated to be functional. The presence of both UbL and J-domains in sacsin suggests that it may integrate the ubiquitin–proteasome system and Hsp70 function to a specific cellular role. The Hsp70 chaperone machinery is an important component of the cellular response towards aggregation prone mutant proteins that are associated with neurodegenerative diseases. We therefore investigated the effects of siRNA-mediated sacsin knockdown on polyglutamine-expanded ataxin-1. Importantly, SACS siRNA did not affect cell viability with GFP-ataxin-1[30Q], but enhanced the toxicity of GFP-ataxin- 1[82Q], suggesting that sacsin is protective against mutant ataxin-1. Thus, sacsin is an ataxia protein and a regulator of the Hsp70 chaperone machinery that is implicated in the processing of other ataxialinked proteins.
- Full Text:
- Authors: Parfitt, David A , Michael, Gregory J , Vermeulen, Esmeralda G M , Prodromou, Natalia V , Webb, Tom R , Gallo, Jean-Marc , Cheetham, Michael E , Nicoll, William S , Blatch, Gregory L , Chapple, J Paul
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6485 , http://hdl.handle.net/10962/d1006262 , http://hmg.oxfordjournals.org/content/18/9/1556
- Description: An extensive protein–protein interaction network has been identified between proteins implicated in inherited ataxias. The protein sacsin, which is mutated in the early-onset neurodegenerative disease autosomal recessive spastic ataxia of Charlevoix-Saguenay, is a node in this interactome. Here, we have established the neuronal expression of sacsin and functionally characterized domains of the 4579 amino acid protein. Sacsin is most highly expressed in large neurons, particularly within brain motor systems, including cerebellar Purkinje cells. Its subcellular localization in SH-SY5Y neuroblastoma cells was predominantly cytoplasmic with a mitochondrial component. We identified a putative ubiquitin-like (UbL) domain at the N-terminus of sacsin and demonstrated an interaction with the proteasome. Furthermore, sacsin contains a predicted J-domain, the defining feature of DnaJ/Hsp40 proteins. Using a bacterial complementation assay, the sacsin J-domain was demonstrated to be functional. The presence of both UbL and J-domains in sacsin suggests that it may integrate the ubiquitin–proteasome system and Hsp70 function to a specific cellular role. The Hsp70 chaperone machinery is an important component of the cellular response towards aggregation prone mutant proteins that are associated with neurodegenerative diseases. We therefore investigated the effects of siRNA-mediated sacsin knockdown on polyglutamine-expanded ataxin-1. Importantly, SACS siRNA did not affect cell viability with GFP-ataxin-1[30Q], but enhanced the toxicity of GFP-ataxin- 1[82Q], suggesting that sacsin is protective against mutant ataxin-1. Thus, sacsin is an ataxia protein and a regulator of the Hsp70 chaperone machinery that is implicated in the processing of other ataxialinked proteins.
- Full Text:
The TPR2B domain of the Hsp70/Hsp90 organizing protein (Hop) may contribute towards its dimerization
- Longshaw, Victoria M, Stephens, Linda L, Daniel, Sheril, Blatch, Gregory L
- Authors: Longshaw, Victoria M , Stephens, Linda L , Daniel, Sheril , Blatch, Gregory L
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6481 , http://hdl.handle.net/10962/d1006253 , http://dx.doi.org/10.2174/092986609787848162
- Description: The role of the TPR2B domain of Hop is as yet unknown. We have shown here by site directed mutagenesis and size exclusion chromatography for the first time that the TPR1 and TPR2B domains of Hop independently dimerized, and that the dimerization of TPR2B was not dependent on its predicted two-carboxylate clamp residues. Furthermore, our data indicated that the dimerization of Hop and its domains was not disrupted in the presence of Hsp70 and Hsp90 peptides.
- Full Text:
The TPR2B domain of the Hsp70/Hsp90 organizing protein (Hop) may contribute towards its dimerization
- Authors: Longshaw, Victoria M , Stephens, Linda L , Daniel, Sheril , Blatch, Gregory L
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6481 , http://hdl.handle.net/10962/d1006253 , http://dx.doi.org/10.2174/092986609787848162
- Description: The role of the TPR2B domain of Hop is as yet unknown. We have shown here by site directed mutagenesis and size exclusion chromatography for the first time that the TPR1 and TPR2B domains of Hop independently dimerized, and that the dimerization of TPR2B was not dependent on its predicted two-carboxylate clamp residues. Furthermore, our data indicated that the dimerization of Hop and its domains was not disrupted in the presence of Hsp70 and Hsp90 peptides.
- Full Text:
- «
- ‹
- 1
- ›
- »