Tiago F Outeiro | University of Göttingen Medical Centre (original) (raw)
Papers by Tiago F Outeiro
Biomolecules, 2015
Parkinson's Disease (PD) is a com... more Parkinson's Disease (PD) is a complex neurodegenerative disorder classically characterized by movement impairment. Pathologically, the most striking features of PD are the loss of dopaminergic neurons and the presence of intraneuronal protein inclusions primarily composed of alpha-synuclein (α-syn) that are known as Lewy bodies and Lewy neurites in surviving neurons. Though the mechanisms underlying the progression of PD pathology are unclear, accumulating evidence suggests a prion-like spreading of α-syn pathology. The intracellular homeostasis of α-syn requires the proper degradation of the protein by three mechanisms: chaperone-mediated autophagy, macroautophagy and ubiquitin-proteasome. Impairment of these pathways might drive the system towards an alternative clearance mechanism that could involve its release from the cell. This increased release to the extracellular space could be the basis for α-syn propagation to different brain areas and, ultimately, for the spreading of pathology and disease progression. Here, we review the interplay between α-syn degradation pathways and its intercellular spreading. The understanding of this interplay is indispensable for obtaining a better knowledge of the molecular basis of PD and, consequently, for the design of novel avenues for therapeutic intervention.
Perspectives in medicinal chemistry, 2008
The heterogeneity of symptoms and disease progression observed in synucleinopathies, of which Par... more The heterogeneity of symptoms and disease progression observed in synucleinopathies, of which Parkinson's disease (PD) is the most common representative, poses large problems for the discovery of novel therapeutics. The molecular basis for pathology is currently unclear, both in familial and in sporadic cases. While the therapeutic effects of L-DOPA and dopamine receptor agonists constitute good options for symptomatic treatment in PD, the development of neuroprotective and/or neurorestorative treatments for PD and other synucleinopathies faces significant challenges due to the poor knowledge of the putative targets. Recent experimental evidence strongly suggests a central role for neurotoxic alpha-synuclein oligomeric species in neurodegeneration. The events leading to protein oligomerization, as well as the oligomeric species themselves, are likely amenable to modulation by small molecules, which are beginning to emerge in high throughput compound screens in a variety of model...
PLOS One, 2009
Background: Oligomerization and aggregation of a-synuclein molecules play a major role in neurona... more Background: Oligomerization and aggregation of a-synuclein molecules play a major role in neuronal dysfunction and loss in Parkinson's disease . However, a-synuclein oligomerization and aggregation have mostly been detected indirectly in cells using detergent extraction methods . A number of in vitro studies showed that dopamine can modulate the aggregation of a-synuclein by inhibiting the formation of or by disaggregating amyloid fibrils .
Science (New York, N.Y.), Jan 27, 2007
The sirtuins are members of the histone deacetylase family of proteins that participate in a vari... more The sirtuins are members of the histone deacetylase family of proteins that participate in a variety of cellular functions and play a role in aging. We identified a potent inhibitor of sirtuin 2 (SIRT2) and found that inhibition of SIRT2 rescued alpha-synuclein toxicity and modified inclusion morphology in a cellular model of Parkinson's disease. Genetic inhibition of SIRT2 via small interfering RNA similarly rescued alpha-synuclein toxicity. Furthermore, the inhibitors protected against dopaminergic cell death both in vitro and in a Drosophila model of Parkinson's disease. The results suggest a link between neurodegeneration and aging.
Journal of Biological Chemistry, 2014
Background: Phosphorylation and sumoylation are post-translational modifications of the Parkinson... more Background: Phosphorylation and sumoylation are post-translational modifications of the Parkinson disease protein ␣-synuclein. Results: ␣-Synuclein inclusion clearance is impaired in yeast when sumoylation is inhibited; phosphorylation of ␣-synuclein can compensate SUMO impairment. Conclusion: Sumoylation stimulates autophagy clearance of ␣-synuclein inclusions, whereas phosphorylation promotes autophagy and proteasome degradation. Significance: A complex molecular post-translational cross-talk is required in yeast to clear toxic inclusions.
Proceedings of the National Academy of Sciences of the United States of America, Jan 13, 2014
The yeast Hsp31 minifamily proteins (Hsp31, Hsp32, Hsp33, Hsp34) belong to the highly conserved D... more The yeast Hsp31 minifamily proteins (Hsp31, Hsp32, Hsp33, Hsp34) belong to the highly conserved DJ-1 superfamily. The human DJ-1 protein is associated with cancer and neurodegenerative disorders, such as Parkinson disease. However, the precise function of human and yeast DJ-1 proteins is unclear. Here we show that the yeast DJ-1 homologs have a role in diauxic-shift (DS), characterized by metabolic reprogramming because of glucose limitation. We find that the Hsp31 genes are strongly induced in DS and in stationary phase (SP), and that deletion of these genes reduces chronological lifespan, impairs transcriptional reprogramming at DS, and impairs the acquisition of several typical characteristics of SP, including autophagy induction. In addition, under carbon starvation, the HSP31 family gene-deletion strains display impaired autophagy, disrupted target of rapamycin complex 1 (TORC1) localization to P-bodies, and caused abnormal TORC1-mediated Atg13 phosphorylation. Repression of TO...
Nature Communications, 2014
α-synuclein is an abundant presynaptic protein that is important for regulation of synaptic vesic... more α-synuclein is an abundant presynaptic protein that is important for regulation of synaptic vesicle trafficking, and whose misfolding plays a key role in Parkinson's disease. While α-synuclein is disordered in solution, it folds into a helical conformation when bound to synaptic vesicles. Stabilization of helical, folded α-synuclein might therefore interfere with α-synuclein-induced neurotoxicity. Here we show that several small molecules, which delay aggregation of α-synuclein in solution, including the Parkinson's disease drug selegiline, fail to interfere with misfolding of vesicle-bound α-synuclein. In contrast, the porphyrin phtalocyanine tetrasulfonate directly binds to vesicle-bound α-synuclein, stabilizes its helical conformation and thereby delays pathogenic misfolding and aggregation. Our study suggests that small-molecule-mediated stabilization of helical vesicle-bound α-synuclein opens new possibilities to target Parkinson's disease and related synucleinopathies.
Human Molecular Genetics, 2014
A central pathological hallmark of Parkinson's disease (PD) is the presence of proteinaceous depo... more A central pathological hallmark of Parkinson's disease (PD) is the presence of proteinaceous depositions known as Lewy bodies, which consist largely of the protein -synuclein (aSyn).
The Journal of biological chemistry, Jan 5, 2015
Although α-synuclein (α-syn) phosphorylation has been considered as a hallmark of sporadic and fa... more Although α-synuclein (α-syn) phosphorylation has been considered as a hallmark of sporadic and familial Parkinson's disease (PD), little is known about the effect of PD-linked mutations on α-syn phosphorylation. In this study, we investigated the effect of the A30P, E46K, and A53T PD-linked mutations on α-syn phosphorylation at residues S87 and S129. Whereas the A30P and A53T mutants slightly affected pS129 levels compared to WT α-syn, the E46K mutation significantly enhanced S129 phosphorylation in yeast and mammalian cell lines. This effect was not due to the E46K mutant being a better kinase substrate, nor due to alterations in endogenous kinase levels, but mostly linked with enhanced nuclear and ER accumulation. Importantly, lentiviral mediated overexpression in mice also showed enhanced pS129 phosphorylation of the E46K mutant compared to WT α-syn, thus providing in vivo validation of our findings. Altogether, our findings suggest that the different PD-linked mutations may ...
Journal of Huntington's disease, 2013
Huntington&am... more Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the abnormal expansion of a CAG triplet repeat tract in the huntingtin gene. While the length of this CAG expansion is the major determinant of the age of onset (AO), other genetic factors have also been shown to play a modulatory role. Recent evidence suggests that neuroinflammations is a pivotal factor in the pathogenesis of HD, and that targeting this process may have important therapeutic ramifications. The human β-defensin 2 (hBD2)- encoded by DEFB4- is an antimicrobial peptide that exhibits inducible expression in astrocytes during inflammation and is an important regulator of innate and adaptive immune response. Therefore, DEFB4 may contribute to the neuroinflammatory processes observed in HD. In this study we tested the hypothesis that copy number variation (CNV) of the β-defensin region, including DEFB4, modifies the AO in HD. We genotyped β-defensin CNV in 490 HD individuals using the paralogue ratio test and found no association between β-defensin CNV and onset of HD. We conclude that it is unlikely that DEFB4 plays a role in HD pathogenesis.
Human Molecular Genetics, 2014
Protein misfolding and aggregation is a major hallmark of neurodegenerative disorders such as Alz... more Protein misfolding and aggregation is a major hallmark of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). Until recently, the consensus was that each aggregation-prone protein was characteristic of each disorder [α-synuclein (α-syn)/PD, mutant huntingtin (Htt)/HD, Tau and amyloid beta peptide/AD]. However, growing evidence indicates that aggregation-prone proteins can actually co-aggregate and modify each other's behavior and toxicity, suggesting that this process may also contribute to the overlap in clinical symptoms across different diseases. Here, we show that α-syn and mutant Htt co-aggregate in vivo when co-expressed in Drosophila and produce a synergistic age-dependent increase in neurotoxicity associated to a decline in motor function and life span. Altogether, our results suggest that the co-existence of α-syn and Htt in the same neuronal cells worsens aggregation-related neuropathologies and accelerates disease progression.
Alpha-synuclein (α-syn) is a soluble protein highly enriched in presynaptic terminals of neurons.... more Alpha-synuclein (α-syn) is a soluble protein highly enriched in presynaptic terminals of neurons. Accumulation of α-syn as intracellular filamentous aggregates is a pathological feature of sporadic and familial forms of Parkinson's disease (PD). Changes in α-syn post-translational modifications, as well as mitochondrial dysfunction and oxidative stress constitute key pathogenic events of this disorder. Here we assessed the correlation between α-syn phosphorylation at serine 129 (Ser129), the formation of reactive oxygen species (ROS) and mitochondrial dysfunction in SH-SY5Y cells expressing A53T mutant or wild-type (WT) α-syn, exposed to ferrous iron (FeSO 4 ) and rotenone (complex I inhibitor). Under basal conditions, prolonged expression of A53T mutant α-syn altered mitochondria morphology, increased superoxide formation and phosphorylation at Ser129, which was linked to decreased activity of protein phosphatase 2A (PP2A). Exposure to FeSO 4 or rotenone enhanced intracellular ROS levels, including superoxide anions, in both types of cells, along with α-syn Ser129 phosphorylation and mitochondrial depolarization. Most of these changes were largely evident in A53T mutant α-syn expressing cells. Overall, the data suggest that stimuli that promote ROS formation and mitochondrial alterations highly correlate with mutant α-syn phosphorylation at Ser129, which may precede cell degeneration in PD.
Front Mol Neurosci, 2014
Protein misfolding and aggregation is a common hallmark in neurodegenerative disorders, including... more Protein misfolding and aggregation is a common hallmark in neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and fronto-temporal dementia (FTD). In these disorders, the misfolding and aggregation of specific proteins occurs alongside neuronal degeneration in somewhat specific brain areas, depending on the disorder and the stage of the disease. However, we still do not fully understand the mechanisms governing protein aggregation, and whether this constitutes a protective or detrimental process. In PD, alpha-synuclein (aSyn) forms protein aggregates, known as Lewy bodies, and is phosphorylated at serine 129. Other residues have also been shown to be phosphorylated, but the significance of phosphorylation in the biology and pathophysiology of the protein is still controversial. In AD and in FTD, hyperphosphorylation of tau protein causes its misfolding and aggregation. Again, our understanding of the precise consequences of tau phosphorylation in the biology and pathophysiology of the protein is still limited. Through the use of a variety of model organisms and technical approaches, we are now gaining stronger insight into the effects of phosphorylation in the behavior of these proteins. In this review, we cover recent findings in the field and discuss how targeting phosphorylation events might be used for therapeutic intervention in these devastating diseases of the nervous system.
Journal of Alzheimer's Disease, 2010
Alzheimer&amp... more Alzheimer's disease (AD) is a complex disorder of the central nervous system that affects an increasing number of people worldwide due to the overall aging of the human population. In addition to genetics, which accounts for a small fraction of all cases, the etiology is multifactorial with other currently unknown triggers. It is crucial to unravel the physiological mechanisms that, being disrupted, could lead to neurodegeneration, as this knowledge could ultimately lead to the identification of novel neuroprotective strategies that could be used as therapeutics. Although mitochondrial dysfunction and the resultant oxidative stress are believed to play a major role in the pathogenesis of both early- and late-onset AD, it is conceivable that the altered physiological state of the cells leading to sporadic AD could involve additional mechanisms. Much evidence suggests that epigenetic modification of gene expression can accumulate with age leading to an altered response to stress and to an enhanced susceptibility to diseases. Since aging has a major impact in different late-onset, complex diseases and, in particular, in the late-onset forms of AD, epigenetic alterations might play an important role in the pathophysiology of this disorder. Studies exploring this idea are underway and suggest that both methylation abnormalities in AD-related genes due to disruption of mechanisms that regulate the availability of methyl groups (SAM/HCY cycle) and changes of global histone acetylation levels might play a role in neurodegeneration. Thus, it is essential to undertake novel global approaches, which may lead to the development of new avenues for therapeutic intervention.
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2011
Several diseases are known to have a multifactorial origin, depending not only on genetic but als... more Several diseases are known to have a multifactorial origin, depending not only on genetic but also on environmental factors. They are called "complex disorders" and include cardiovascular disease, cancer, diabetes, and neuropsychiatric and neurodegenerative diseases. In the latter class, Alzheimer's (AD) and Parkinson's diseases (PD) are by far the most common in the elderly and constitute a tremendous social and economical problem. Both disorders present familial and sporadic forms and although some polymorphisms and risk factors have been associated with AD and PD, the precise way by which the environment contributes to neurodegeneration is still unclear. Recent studies suggest that environmental factors may contribute for neurodegeneration through induction of epigenetic modifications, such as DNA methylation, and chromatin remodeling, which may induce alterations in gene expression programs. Epigenetics, which refers to any process that alters gene activity without changing the actual DNA sequence, and leads to modifications that can be transmitted to daughter cells, is a relatively novel area of research that is currently attracting a high level of interest. Epigenetic modulation is present since the prenatal stages, and the aging process is now accepted to be associated with a loss of phenotypic plasticity to epigenetic modifications. Since aging is the most important risk factor for idiopathic AD and PD, it is expected that epigenetic alterations on DNA and/or chromatin structure may also accumulate in neurodegeneration, accounting at least in part to the etiology of these disorders.
Disease models & mechanisms
alpha-Synuclein (alpha-syn) is a small lipid-binding protein involved in vesicle trafficking whos... more alpha-Synuclein (alpha-syn) is a small lipid-binding protein involved in vesicle trafficking whose function is poorly characterized. It is of great interest to human biology and medicine because alpha-syn dysfunction is associated with several neurodegenerative disorders, including Parkinson's disease (PD). We previously created a yeast model of alpha-syn pathobiology, which established vesicle trafficking as a process that is particularly sensitive to alpha-syn expression. We also uncovered a core group of proteins with diverse activities related to alpha-syn toxicity that is conserved from yeast to mammalian neurons. Here, we report that a yeast strain expressing a somewhat higher level of alpha-syn also exhibits strong defects in mitochondrial function. Unlike our previous strain, genetic suppression of endoplasmic reticulum (ER)-to-Golgi trafficking alone does not suppress alpha-syn toxicity in this strain. In an effort to identify individual compounds that could simultaneou...
PROTEOMICS - Clinical Applications, 2010
Abreviations: AL -amyloidosis ATTR -Transthyretin amyloidosis FTICR-MS -Fourier transform ion-cyc... more Abreviations: AL -amyloidosis ATTR -Transthyretin amyloidosis FTICR-MS -Fourier transform ion-cyclotron resonance mass spectrometry FAP -familial amyloid polyneuropathy V30M -replacement of valine at position 30 by methionine in TTR sequence Abstract Purpose: To identify, characterize and perform a relative quantification of human transthyretin (TTR) variants in human saliva. Experimental design: Serum and saliva samples were collected from healthy and familial amyloidotic polyneuropathy (FAP) patients, proteins separated by SDS-PAGE, TTR bands excised, in-gel digested and analyzed by MALDI-FTICR. Results: We identified and performed a relative quantification of mutated and native TTR forms in human saliva, based on FTICR-MS. The results are quantitatively identical to the ones obtained with human serum. In FAP patients subjected to cadaveric liver transplant, the TTR mutant form is no longer detected in saliva, while in patients receiving a domino liver from a FAP donor the mutant form of TTR becomes detectable in saliva, thus demonstrating the serum origin of TTR in saliva.
Experimental neurobiology, 2014
Parkinson's Disease (PD) is a complex and multifactorial disorder of both idiopathic and gene... more Parkinson's Disease (PD) is a complex and multifactorial disorder of both idiopathic and genetic origin. Thus far, more than 20 genes have been linked to familial forms of PD. Two of these genes encode for ATP13A2 and alpha-synuclein (asyn), proteins that seem to be members of a common network in both physiological and disease conditions. Thus, two different hypotheses have emerged supporting a role of ATP13A2 and asyn in metal homeostasis or in autophagy. Interestingly, an appealing theory might combine these two cellular pathways. Here we review the novel findings in the interaction between these two proteins and debate the exciting roads still ahead.
The FASEB Journal, 2006
Oligomerization and aggregation of ␣-synuclein molecules are believed to play a major role in neu... more Oligomerization and aggregation of ␣-synuclein molecules are believed to play a major role in neuronal dysfunction and loss in Parkinson's disease (PD) and dementia with Lewy bodies. However, ␣-synuclein oligomerization and aggregation have been detected only indirectly in cells using detergent extraction methods. Here, we show for the first time intracellular ␣-synuclein oligomerization using fluorescence lifetime imaging (FLIM). Two forms of ␣-synuclein homomeric interactions were detected: an antiparallel amino terminus-carboxyl terminus interaction between ␣-synuclein molecules, and a close amino terminuscarboxy terminus interaction within single ␣-synuclein molecules. Coexpression of the chaperone protein Hsp70, which can block ␣-synuclein toxicity in several systems, causes ␣-synuclein to adopt a different, open conformation, but Hsp70 does not alter ␣-synuclein-␣synuclein interactions. Thus, the neuroprotective effect of Hsp70 can be explained by its chaperone activity on ␣-synuclein molecules, rather than alteration of ␣-synuclein-␣-synuclein interactions.-Klucken, J., Outeiro, T. F., Nyugen, P., McLean, P. J., and Hyman, B. T. Detection of novel intracellular ␣-synuclein oligomeric species by fluorescence lifetime imaging. FASEB
Biomolecules, 2015
Parkinson's Disease (PD) is a com... more Parkinson's Disease (PD) is a complex neurodegenerative disorder classically characterized by movement impairment. Pathologically, the most striking features of PD are the loss of dopaminergic neurons and the presence of intraneuronal protein inclusions primarily composed of alpha-synuclein (α-syn) that are known as Lewy bodies and Lewy neurites in surviving neurons. Though the mechanisms underlying the progression of PD pathology are unclear, accumulating evidence suggests a prion-like spreading of α-syn pathology. The intracellular homeostasis of α-syn requires the proper degradation of the protein by three mechanisms: chaperone-mediated autophagy, macroautophagy and ubiquitin-proteasome. Impairment of these pathways might drive the system towards an alternative clearance mechanism that could involve its release from the cell. This increased release to the extracellular space could be the basis for α-syn propagation to different brain areas and, ultimately, for the spreading of pathology and disease progression. Here, we review the interplay between α-syn degradation pathways and its intercellular spreading. The understanding of this interplay is indispensable for obtaining a better knowledge of the molecular basis of PD and, consequently, for the design of novel avenues for therapeutic intervention.
Perspectives in medicinal chemistry, 2008
The heterogeneity of symptoms and disease progression observed in synucleinopathies, of which Par... more The heterogeneity of symptoms and disease progression observed in synucleinopathies, of which Parkinson's disease (PD) is the most common representative, poses large problems for the discovery of novel therapeutics. The molecular basis for pathology is currently unclear, both in familial and in sporadic cases. While the therapeutic effects of L-DOPA and dopamine receptor agonists constitute good options for symptomatic treatment in PD, the development of neuroprotective and/or neurorestorative treatments for PD and other synucleinopathies faces significant challenges due to the poor knowledge of the putative targets. Recent experimental evidence strongly suggests a central role for neurotoxic alpha-synuclein oligomeric species in neurodegeneration. The events leading to protein oligomerization, as well as the oligomeric species themselves, are likely amenable to modulation by small molecules, which are beginning to emerge in high throughput compound screens in a variety of model...
PLOS One, 2009
Background: Oligomerization and aggregation of a-synuclein molecules play a major role in neurona... more Background: Oligomerization and aggregation of a-synuclein molecules play a major role in neuronal dysfunction and loss in Parkinson's disease . However, a-synuclein oligomerization and aggregation have mostly been detected indirectly in cells using detergent extraction methods . A number of in vitro studies showed that dopamine can modulate the aggregation of a-synuclein by inhibiting the formation of or by disaggregating amyloid fibrils .
Science (New York, N.Y.), Jan 27, 2007
The sirtuins are members of the histone deacetylase family of proteins that participate in a vari... more The sirtuins are members of the histone deacetylase family of proteins that participate in a variety of cellular functions and play a role in aging. We identified a potent inhibitor of sirtuin 2 (SIRT2) and found that inhibition of SIRT2 rescued alpha-synuclein toxicity and modified inclusion morphology in a cellular model of Parkinson's disease. Genetic inhibition of SIRT2 via small interfering RNA similarly rescued alpha-synuclein toxicity. Furthermore, the inhibitors protected against dopaminergic cell death both in vitro and in a Drosophila model of Parkinson's disease. The results suggest a link between neurodegeneration and aging.
Journal of Biological Chemistry, 2014
Background: Phosphorylation and sumoylation are post-translational modifications of the Parkinson... more Background: Phosphorylation and sumoylation are post-translational modifications of the Parkinson disease protein ␣-synuclein. Results: ␣-Synuclein inclusion clearance is impaired in yeast when sumoylation is inhibited; phosphorylation of ␣-synuclein can compensate SUMO impairment. Conclusion: Sumoylation stimulates autophagy clearance of ␣-synuclein inclusions, whereas phosphorylation promotes autophagy and proteasome degradation. Significance: A complex molecular post-translational cross-talk is required in yeast to clear toxic inclusions.
Proceedings of the National Academy of Sciences of the United States of America, Jan 13, 2014
The yeast Hsp31 minifamily proteins (Hsp31, Hsp32, Hsp33, Hsp34) belong to the highly conserved D... more The yeast Hsp31 minifamily proteins (Hsp31, Hsp32, Hsp33, Hsp34) belong to the highly conserved DJ-1 superfamily. The human DJ-1 protein is associated with cancer and neurodegenerative disorders, such as Parkinson disease. However, the precise function of human and yeast DJ-1 proteins is unclear. Here we show that the yeast DJ-1 homologs have a role in diauxic-shift (DS), characterized by metabolic reprogramming because of glucose limitation. We find that the Hsp31 genes are strongly induced in DS and in stationary phase (SP), and that deletion of these genes reduces chronological lifespan, impairs transcriptional reprogramming at DS, and impairs the acquisition of several typical characteristics of SP, including autophagy induction. In addition, under carbon starvation, the HSP31 family gene-deletion strains display impaired autophagy, disrupted target of rapamycin complex 1 (TORC1) localization to P-bodies, and caused abnormal TORC1-mediated Atg13 phosphorylation. Repression of TO...
Nature Communications, 2014
α-synuclein is an abundant presynaptic protein that is important for regulation of synaptic vesic... more α-synuclein is an abundant presynaptic protein that is important for regulation of synaptic vesicle trafficking, and whose misfolding plays a key role in Parkinson's disease. While α-synuclein is disordered in solution, it folds into a helical conformation when bound to synaptic vesicles. Stabilization of helical, folded α-synuclein might therefore interfere with α-synuclein-induced neurotoxicity. Here we show that several small molecules, which delay aggregation of α-synuclein in solution, including the Parkinson's disease drug selegiline, fail to interfere with misfolding of vesicle-bound α-synuclein. In contrast, the porphyrin phtalocyanine tetrasulfonate directly binds to vesicle-bound α-synuclein, stabilizes its helical conformation and thereby delays pathogenic misfolding and aggregation. Our study suggests that small-molecule-mediated stabilization of helical vesicle-bound α-synuclein opens new possibilities to target Parkinson's disease and related synucleinopathies.
Human Molecular Genetics, 2014
A central pathological hallmark of Parkinson's disease (PD) is the presence of proteinaceous depo... more A central pathological hallmark of Parkinson's disease (PD) is the presence of proteinaceous depositions known as Lewy bodies, which consist largely of the protein -synuclein (aSyn).
The Journal of biological chemistry, Jan 5, 2015
Although α-synuclein (α-syn) phosphorylation has been considered as a hallmark of sporadic and fa... more Although α-synuclein (α-syn) phosphorylation has been considered as a hallmark of sporadic and familial Parkinson's disease (PD), little is known about the effect of PD-linked mutations on α-syn phosphorylation. In this study, we investigated the effect of the A30P, E46K, and A53T PD-linked mutations on α-syn phosphorylation at residues S87 and S129. Whereas the A30P and A53T mutants slightly affected pS129 levels compared to WT α-syn, the E46K mutation significantly enhanced S129 phosphorylation in yeast and mammalian cell lines. This effect was not due to the E46K mutant being a better kinase substrate, nor due to alterations in endogenous kinase levels, but mostly linked with enhanced nuclear and ER accumulation. Importantly, lentiviral mediated overexpression in mice also showed enhanced pS129 phosphorylation of the E46K mutant compared to WT α-syn, thus providing in vivo validation of our findings. Altogether, our findings suggest that the different PD-linked mutations may ...
Journal of Huntington's disease, 2013
Huntington&am... more Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the abnormal expansion of a CAG triplet repeat tract in the huntingtin gene. While the length of this CAG expansion is the major determinant of the age of onset (AO), other genetic factors have also been shown to play a modulatory role. Recent evidence suggests that neuroinflammations is a pivotal factor in the pathogenesis of HD, and that targeting this process may have important therapeutic ramifications. The human β-defensin 2 (hBD2)- encoded by DEFB4- is an antimicrobial peptide that exhibits inducible expression in astrocytes during inflammation and is an important regulator of innate and adaptive immune response. Therefore, DEFB4 may contribute to the neuroinflammatory processes observed in HD. In this study we tested the hypothesis that copy number variation (CNV) of the β-defensin region, including DEFB4, modifies the AO in HD. We genotyped β-defensin CNV in 490 HD individuals using the paralogue ratio test and found no association between β-defensin CNV and onset of HD. We conclude that it is unlikely that DEFB4 plays a role in HD pathogenesis.
Human Molecular Genetics, 2014
Protein misfolding and aggregation is a major hallmark of neurodegenerative disorders such as Alz... more Protein misfolding and aggregation is a major hallmark of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). Until recently, the consensus was that each aggregation-prone protein was characteristic of each disorder [α-synuclein (α-syn)/PD, mutant huntingtin (Htt)/HD, Tau and amyloid beta peptide/AD]. However, growing evidence indicates that aggregation-prone proteins can actually co-aggregate and modify each other's behavior and toxicity, suggesting that this process may also contribute to the overlap in clinical symptoms across different diseases. Here, we show that α-syn and mutant Htt co-aggregate in vivo when co-expressed in Drosophila and produce a synergistic age-dependent increase in neurotoxicity associated to a decline in motor function and life span. Altogether, our results suggest that the co-existence of α-syn and Htt in the same neuronal cells worsens aggregation-related neuropathologies and accelerates disease progression.
Alpha-synuclein (α-syn) is a soluble protein highly enriched in presynaptic terminals of neurons.... more Alpha-synuclein (α-syn) is a soluble protein highly enriched in presynaptic terminals of neurons. Accumulation of α-syn as intracellular filamentous aggregates is a pathological feature of sporadic and familial forms of Parkinson's disease (PD). Changes in α-syn post-translational modifications, as well as mitochondrial dysfunction and oxidative stress constitute key pathogenic events of this disorder. Here we assessed the correlation between α-syn phosphorylation at serine 129 (Ser129), the formation of reactive oxygen species (ROS) and mitochondrial dysfunction in SH-SY5Y cells expressing A53T mutant or wild-type (WT) α-syn, exposed to ferrous iron (FeSO 4 ) and rotenone (complex I inhibitor). Under basal conditions, prolonged expression of A53T mutant α-syn altered mitochondria morphology, increased superoxide formation and phosphorylation at Ser129, which was linked to decreased activity of protein phosphatase 2A (PP2A). Exposure to FeSO 4 or rotenone enhanced intracellular ROS levels, including superoxide anions, in both types of cells, along with α-syn Ser129 phosphorylation and mitochondrial depolarization. Most of these changes were largely evident in A53T mutant α-syn expressing cells. Overall, the data suggest that stimuli that promote ROS formation and mitochondrial alterations highly correlate with mutant α-syn phosphorylation at Ser129, which may precede cell degeneration in PD.
Front Mol Neurosci, 2014
Protein misfolding and aggregation is a common hallmark in neurodegenerative disorders, including... more Protein misfolding and aggregation is a common hallmark in neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and fronto-temporal dementia (FTD). In these disorders, the misfolding and aggregation of specific proteins occurs alongside neuronal degeneration in somewhat specific brain areas, depending on the disorder and the stage of the disease. However, we still do not fully understand the mechanisms governing protein aggregation, and whether this constitutes a protective or detrimental process. In PD, alpha-synuclein (aSyn) forms protein aggregates, known as Lewy bodies, and is phosphorylated at serine 129. Other residues have also been shown to be phosphorylated, but the significance of phosphorylation in the biology and pathophysiology of the protein is still controversial. In AD and in FTD, hyperphosphorylation of tau protein causes its misfolding and aggregation. Again, our understanding of the precise consequences of tau phosphorylation in the biology and pathophysiology of the protein is still limited. Through the use of a variety of model organisms and technical approaches, we are now gaining stronger insight into the effects of phosphorylation in the behavior of these proteins. In this review, we cover recent findings in the field and discuss how targeting phosphorylation events might be used for therapeutic intervention in these devastating diseases of the nervous system.
Journal of Alzheimer's Disease, 2010
Alzheimer&amp... more Alzheimer's disease (AD) is a complex disorder of the central nervous system that affects an increasing number of people worldwide due to the overall aging of the human population. In addition to genetics, which accounts for a small fraction of all cases, the etiology is multifactorial with other currently unknown triggers. It is crucial to unravel the physiological mechanisms that, being disrupted, could lead to neurodegeneration, as this knowledge could ultimately lead to the identification of novel neuroprotective strategies that could be used as therapeutics. Although mitochondrial dysfunction and the resultant oxidative stress are believed to play a major role in the pathogenesis of both early- and late-onset AD, it is conceivable that the altered physiological state of the cells leading to sporadic AD could involve additional mechanisms. Much evidence suggests that epigenetic modification of gene expression can accumulate with age leading to an altered response to stress and to an enhanced susceptibility to diseases. Since aging has a major impact in different late-onset, complex diseases and, in particular, in the late-onset forms of AD, epigenetic alterations might play an important role in the pathophysiology of this disorder. Studies exploring this idea are underway and suggest that both methylation abnormalities in AD-related genes due to disruption of mechanisms that regulate the availability of methyl groups (SAM/HCY cycle) and changes of global histone acetylation levels might play a role in neurodegeneration. Thus, it is essential to undertake novel global approaches, which may lead to the development of new avenues for therapeutic intervention.
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2011
Several diseases are known to have a multifactorial origin, depending not only on genetic but als... more Several diseases are known to have a multifactorial origin, depending not only on genetic but also on environmental factors. They are called "complex disorders" and include cardiovascular disease, cancer, diabetes, and neuropsychiatric and neurodegenerative diseases. In the latter class, Alzheimer's (AD) and Parkinson's diseases (PD) are by far the most common in the elderly and constitute a tremendous social and economical problem. Both disorders present familial and sporadic forms and although some polymorphisms and risk factors have been associated with AD and PD, the precise way by which the environment contributes to neurodegeneration is still unclear. Recent studies suggest that environmental factors may contribute for neurodegeneration through induction of epigenetic modifications, such as DNA methylation, and chromatin remodeling, which may induce alterations in gene expression programs. Epigenetics, which refers to any process that alters gene activity without changing the actual DNA sequence, and leads to modifications that can be transmitted to daughter cells, is a relatively novel area of research that is currently attracting a high level of interest. Epigenetic modulation is present since the prenatal stages, and the aging process is now accepted to be associated with a loss of phenotypic plasticity to epigenetic modifications. Since aging is the most important risk factor for idiopathic AD and PD, it is expected that epigenetic alterations on DNA and/or chromatin structure may also accumulate in neurodegeneration, accounting at least in part to the etiology of these disorders.
Disease models & mechanisms
alpha-Synuclein (alpha-syn) is a small lipid-binding protein involved in vesicle trafficking whos... more alpha-Synuclein (alpha-syn) is a small lipid-binding protein involved in vesicle trafficking whose function is poorly characterized. It is of great interest to human biology and medicine because alpha-syn dysfunction is associated with several neurodegenerative disorders, including Parkinson's disease (PD). We previously created a yeast model of alpha-syn pathobiology, which established vesicle trafficking as a process that is particularly sensitive to alpha-syn expression. We also uncovered a core group of proteins with diverse activities related to alpha-syn toxicity that is conserved from yeast to mammalian neurons. Here, we report that a yeast strain expressing a somewhat higher level of alpha-syn also exhibits strong defects in mitochondrial function. Unlike our previous strain, genetic suppression of endoplasmic reticulum (ER)-to-Golgi trafficking alone does not suppress alpha-syn toxicity in this strain. In an effort to identify individual compounds that could simultaneou...
PROTEOMICS - Clinical Applications, 2010
Abreviations: AL -amyloidosis ATTR -Transthyretin amyloidosis FTICR-MS -Fourier transform ion-cyc... more Abreviations: AL -amyloidosis ATTR -Transthyretin amyloidosis FTICR-MS -Fourier transform ion-cyclotron resonance mass spectrometry FAP -familial amyloid polyneuropathy V30M -replacement of valine at position 30 by methionine in TTR sequence Abstract Purpose: To identify, characterize and perform a relative quantification of human transthyretin (TTR) variants in human saliva. Experimental design: Serum and saliva samples were collected from healthy and familial amyloidotic polyneuropathy (FAP) patients, proteins separated by SDS-PAGE, TTR bands excised, in-gel digested and analyzed by MALDI-FTICR. Results: We identified and performed a relative quantification of mutated and native TTR forms in human saliva, based on FTICR-MS. The results are quantitatively identical to the ones obtained with human serum. In FAP patients subjected to cadaveric liver transplant, the TTR mutant form is no longer detected in saliva, while in patients receiving a domino liver from a FAP donor the mutant form of TTR becomes detectable in saliva, thus demonstrating the serum origin of TTR in saliva.
Experimental neurobiology, 2014
Parkinson's Disease (PD) is a complex and multifactorial disorder of both idiopathic and gene... more Parkinson's Disease (PD) is a complex and multifactorial disorder of both idiopathic and genetic origin. Thus far, more than 20 genes have been linked to familial forms of PD. Two of these genes encode for ATP13A2 and alpha-synuclein (asyn), proteins that seem to be members of a common network in both physiological and disease conditions. Thus, two different hypotheses have emerged supporting a role of ATP13A2 and asyn in metal homeostasis or in autophagy. Interestingly, an appealing theory might combine these two cellular pathways. Here we review the novel findings in the interaction between these two proteins and debate the exciting roads still ahead.
The FASEB Journal, 2006
Oligomerization and aggregation of ␣-synuclein molecules are believed to play a major role in neu... more Oligomerization and aggregation of ␣-synuclein molecules are believed to play a major role in neuronal dysfunction and loss in Parkinson's disease (PD) and dementia with Lewy bodies. However, ␣-synuclein oligomerization and aggregation have been detected only indirectly in cells using detergent extraction methods. Here, we show for the first time intracellular ␣-synuclein oligomerization using fluorescence lifetime imaging (FLIM). Two forms of ␣-synuclein homomeric interactions were detected: an antiparallel amino terminus-carboxyl terminus interaction between ␣-synuclein molecules, and a close amino terminuscarboxy terminus interaction within single ␣-synuclein molecules. Coexpression of the chaperone protein Hsp70, which can block ␣-synuclein toxicity in several systems, causes ␣-synuclein to adopt a different, open conformation, but Hsp70 does not alter ␣-synuclein-␣synuclein interactions. Thus, the neuroprotective effect of Hsp70 can be explained by its chaperone activity on ␣-synuclein molecules, rather than alteration of ␣-synuclein-␣-synuclein interactions.-Klucken, J., Outeiro, T. F., Nyugen, P., McLean, P. J., and Hyman, B. T. Detection of novel intracellular ␣-synuclein oligomeric species by fluorescence lifetime imaging. FASEB