Kleinknecht, Alexandra

[["dc.bibliographiccitation.firstpage","e1006098"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","PLOS Genetics"],["dc.bibliographiccitation.volume","12"],["dc.contributor.author","Kleinknecht, Alexandra"],["dc.contributor.author","Popova, Blagovesta"],["dc.contributor.author","Lázaro, Diana F."],["dc.contributor.author","Pinho, Raquel"],["dc.contributor.author","Valerius, Oliver"],["dc.contributor.author","Outeiro, Tiago F."],["dc.contributor.author","Braus, Gerhard H."],["dc.contributor.editor","Lu, Bingwei"],["dc.date.accessioned","2018-09-28T07:41:43Z"],["dc.date.available","2018-09-28T07:41:43Z"],["dc.date.issued","2016"],["dc.description.abstract","Parkinson´s disease (PD) is characterized by the presence of proteinaceous inclusions called Lewy bodies that are mainly composed of α-synuclein (αSyn). Elevated levels of oxidative or nitrative stresses have been implicated in αSyn related toxicity. Phosphorylation of αSyn on serine 129 (S129) modulates autophagic clearance of inclusions and is prominently found in Lewy bodies. The neighboring tyrosine residues Y125, Y133 and Y136 are phosphorylation and nitration sites. Using a yeast model of PD, we found that Y133 is required for protective S129 phosphorylation and for S129-independent proteasome clearance. αSyn can be nitrated and form stable covalent dimers originating from covalent crosslinking of two tyrosine residues. Nitrated tyrosine residues, but not di-tyrosine-crosslinked dimers, contributed to αSyn cytotoxicity and aggregation. Analysis of tyrosine residues involved in nitration and crosslinking revealed that the C-terminus, rather than the N-terminus of αSyn, is modified by nitration and di-tyrosine formation. The nitration level of wild-type αSyn was higher compared to that of A30P mutant that is non-toxic in yeast. A30P formed more dimers than wild-type αSyn, suggesting that dimer formation represents a cellular detoxification pathway in yeast. Deletion of the yeast flavohemoglobin gene YHB1 resulted in an increase of cellular nitrative stress and cytotoxicity leading to enhanced aggregation of A30P αSyn. Yhb1 protected yeast from A30P-induced mitochondrial fragmentation and peroxynitrite-induced nitrative stress. Strikingly, overexpression of neuroglobin, the human homolog of YHB1, protected against αSyn inclusion formation in mammalian cells. In total, our data suggest that C-terminal Y133 plays a major role in αSyn aggregate clearance by supporting the protective S129 phosphorylation for autophagy and by promoting proteasome clearance. C-terminal tyrosine nitration increases pathogenicity and can only be partially detoxified by αSyn di-tyrosine dimers. Our findings uncover a complex interplay between S129 phosphorylation and C-terminal tyrosine modifications of αSyn that likely participates in PD pathology."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2016"],["dc.identifier.doi","10.1371/journal.pgen.1006098"],["dc.identifier.pmid","27341336"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/13384"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15831"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.relation.eissn","1553-7404"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","C-Terminal Tyrosine Residue Modifications Modulate the Protective Phosphorylation of Serine 129 of α-Synuclein in a Yeast Model of Parkinson's Disease"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","94"],["dc.bibliographiccitation.journal","Frontiers in Molecular Neuroscience"],["dc.bibliographiccitation.volume","11"],["dc.contributor.author","Popova, Blagovesta"],["dc.contributor.author","Kleinknecht, Alexandra"],["dc.contributor.author","Arendarski, Patricia"],["dc.contributor.author","Mischke, Jasmin"],["dc.contributor.author","Wang, Dan"],["dc.contributor.author","Braus, Gerhard H."],["dc.date.accessioned","2018-09-28T07:27:45Z"],["dc.date.available","2018-09-28T07:27:45Z"],["dc.date.issued","2018"],["dc.description.abstract","Aggregation of α-synuclein (αSyn) plays a central role in the pathogenesis of Parkinson's disease (PD). The budding yeast Saccharomyces cerevisiae serves as reference cell to study the interplay between αSyn misfolding, cytotoxicity and post-translational modifications (PTMs). The synuclein family includes α, β and γ isoforms. β-synuclein (βSyn) and αSyn are found at presynaptic terminals and both proteins are presumably involved in disease pathogenesis. Similar to αSyn, expression of βSyn leads to growth deficiency and formation of intracellular aggregates in yeast. Co-expression of αSyn and βSyn exacerbates the cytotoxicity. This suggests an important role of βSyn homeostasis in PD pathology. We show here that the small ubiquitin-like modifier SUMO is an important determinant of protein stability and βSyn-induced toxicity in eukaryotic cells. Downregulation of sumoylation in a yeast strain, defective for the SUMO-encoding gene resulted in reduced yeast growth, whereas upregulation of sumoylation rescued growth of yeast cell expressing βSyn. This corroborates a protective role of the cellular sumoylation machinery against βSyn-induced toxicity. Upregulation of sumoylation significantly reduced βSyn aggregate formation. This is an indirect molecular process, which is not directly linked to βSyn sumoylation because amino acid substitutions in the lysine residues required for βSyn sumoylation decreased aggregation without changing yeast cellular toxicity. αSyn aggregates are more predominantly degraded by the autophagy/vacuole than by the 26S ubiquitin proteasome system. We demonstrate a vice versa situation for βSyn, which is mainly degraded in the 26S proteasome. Downregulation of sumoylation significantly compromised the clearance of βSyn by the 26S proteasome and increased protein stability. This effect is specific, because depletion of functional SUMO did neither affect βSyn aggregate formation nor its degradation by the autophagy/vacuolar pathway. Our data support that cellular βSyn toxicity and aggregation do not correlate in their cellular impact as for αSyn but rather represent two distinct independent molecular functions and molecular mechanisms. These insights into the relationship between βSyn-induced toxicity, aggregate formation and degradation demonstrate a significant distinction between the impact of αSyn compared to βSyn on eukaryotic cells."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2018"],["dc.identifier.doi","10.3389/fnmol.2018.00094"],["dc.identifier.pmid","29636661"],["dc.identifier.pmid","29636661"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15081"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15830"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.publisher","Frontiers Media S.A."],["dc.relation.eissn","1662-5099"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","Sumoylation Protects Against β-Synuclein Toxicity in Yeast"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]