Nuclear localization and phosphorylation modulate pathological effects of α-synuclein

Alpha-synuclein (aSyn) is a central player in Parkinson's disease (PD) but the precise molecular mechanisms underlying its pathogenicity remain unclear. It has recently been suggested that nuclear aSyn may modulate gene expression, possibly via interactions with DNA. However, the biological behavior of aSyn in the nucleus and the factors affecting its transcriptional role are not known. Here, we investigated the mechanisms underlying aSyn-mediated transcription deregulation by assessing its effects in the nucleus and the impact of phosphorylation in these dynamics. We found that aSyn induced severe transcriptional deregulation, including the downregulation of important cell cycle-related genes. Importantly, transcriptional deregulation was concomitant with reduced binding of aSyn to DNA. By forcing the nuclear presence of aSyn in the nucleus (aSyn-NLS), we found the accumulation of high molecular weight aSyn species altered gene expression and reduced toxicity when compared to the wild-type or exclusively cytosolic protein. Interestingly, nuclear localization of aSyn, and the effect on gene expression and cytotoxicity, was also modulated by phosphorylation on serine 129. Thus, we hypothesize that the role of aSyn on gene expression and, ultimately, toxicity, may be modulated by the phosphorylation status and nuclear presence of different aSyn species. Our findings shed new light onto the subcellular dynamics of aSyn and unveil an intricate interplay between subcellular location, phosphorylation, and toxicity, opening novel avenues for the design of future strategies for therapeutic intervention in PD and other synucleinopathies

Nuclear localization and phosphorylation modulate pathological effects of α-synuclein

Alpha-synuclein (aSyn) is a central player in Parkinson's disease (PD) but the precise molecular mechanisms underlying its pathogenicity remain unclear. It has recently been suggested that nuclear aSyn may modulate gene expression, possibly via interactions with DNA. However, the biological behavior of aSyn in the nucleus and the factors affecting its transcriptional role are not known. Here, we investigated the mechanisms underlying aSyn-mediated transcription deregulation by assessing its effects in the nucleus and the impact of phosphorylation in these dynamics. We found that aSyn induced severe transcriptional deregulation, including the downregulation of important cell cycle-related genes. Importantly, transcriptional deregulation was concomitant with reduced binding of aSyn to DNA. By forcing the nuclear presence of aSyn in the nucleus (aSyn-NLS), we found the accumulation of high molecular weight aSyn species altered gene expression and reduced toxicity when compared to the wild-type or exclusively cytosolic protein. Interestingly, nuclear localization of aSyn, and the effect on gene expression and cytotoxicity, was also modulated by phosphorylation on serine 129. Thus, we hypothesize that the role of aSyn on gene expression and, ultimately, toxicity, may be modulated by the phosphorylation status and nuclear presence of different aSyn species. Our findings shed new light onto the subcellular dynamics of aSyn and unveil an intricate interplay between subcellular location, phosphorylation, and toxicity, opening novel avenues for the design of future strategies for therapeutic intervention in PD and other synucleinopathies

Glycation potentiates α-synuclein-associated neurodegeneration in synucleinopathies

α-Synuclein misfolding and aggregation is a hallmark in Parkinson's disease and in several other neurodegenerative diseases known as synucleinopathies. The toxic properties of α-synuclein are conserved from yeast to man, but the precise underpinnings of the cellular pathologies associated are still elusive, complicating the development of effective therapeutic strategies. Combining molecular genetics with target-based approaches, we established that glycation, an unavoidable age-associated post-translational modification, enhanced α-synuclein toxicity in vitro and in vivo, in Drosophila and in mice. Glycation affected primarily the N-terminal region of α-synuclein, reducing membrane binding, impaired the clearance of α-synuclein, and promoted the accumulation of toxic oligomers that impaired neuronal synaptic transmission. Strikingly, using glycation inhibitors, we demonstrated that normal clearance of α-synuclein was re-established, aggregation was reduced, and motor phenotypes in Drosophila were alleviated. Altogether, our study demonstrates glycation constitutes a novel drug target that can be explored in synucleinopathies as well as in other neurodegenerative conditions.Authors were supported by: H.V.M. (Fundac¸a˜o para a Cieˆncia e Tecnologia (FCT), Portugal SFRH/BPD/64702/ 2009 and SFRH/BPD/109347/2015; EU FP7 project MEFOPA), L.M.A.O (FCT - SFRH/BD/23604/2005; CIRM-BMFB joint grant, 315050 AZ0101-31P6855), R.M.O. and T.S. (FCT SFRH/BPD/41416/2007; SFRH/ BPD/31209/2006); W.X. (Deutsche Forschungsgemeinschaft, SFB539/A3); C.B. and F.G. (Parkinson’s UK and the Medical Research Council, UK). S.E. is supported by Israel Academy of Sciences, Rappaport Family Institute for Research in the Medical Sciences, The Allen and Jewel Prince Center for Neurodegenerative Disorders of the Brain. T.F.O. (EMBO Installation Grant; Marie Curie IRG, Neurofold; DFG Center for Nanoscale Microscopy and Molecular Physiology of the Brain; I.C.M. (FCT SFRH/BPD/74287/2010; Investigador FCT IF/00772/ 2013). This work was supported by: FCT PTDC/SAUNEU/ 105215/2008, PTDC/QUI/73430/2006, PTDC/SAUENB/ 117013/2010, PTDC/NEU-OSD/5644/2014; EU FP7 project MEFOPA; CIRM-BMFB joint grant (315050 AZ0101-31P6855); Max Planck Society; and European Union (NEURASYNC PITNGA-2009-238316).info:eu-repo/semantics/publishedVersio

The mechanism of sirtuin 2–mediated exacerbation of alpha-synuclein toxicity in models of Parkinson disease

Sirtuin genes have been associated with aging and are known to affect multiple cellular pathways. Sirtuin 2 was previously shown to modulate proteotoxicity associated with age-associated neurodegenerative disorders such as Alzheimer and Parkinson disease (PD). However, the precise molecular mechanisms involved remain unclear. Here, we provide mechanistic insight into the interplay between sirtuin 2 and α-synuclein, the major component of the pathognomonic protein inclusions in PD and other synucleinopathies. We found that α-synuclein is acetylated on lysines 6 and 10 and that these residues are deacetylated by sirtuin 2. Genetic manipulation of sirtuin 2 levels in vitro and in vivo modulates the levels of α-synuclein acetylation, its aggregation, and autophagy. Strikingly, mutants blocking acetylation exacerbate α-synuclein toxicity in vivo, in the substantia nigra of rats. Our study identifies α-synuclein acetylation as a key regulatory mechanism governing α-synuclein aggregation and toxicity, demonstrating the potential therapeutic value of sirtuin 2 inhibition in synucleinopathies.Open-Access-Publikationsfonds 2017peerReviewe