Untitled

Funder

Organizational Unit

Publications

Glycation modulates glutamatergic signaling and exacerbates Parkinson’s disease-like phenotypes

Publication . Chegão, Ana; Guarda, Mariana; Alexandre, Bruno M.; Shvachiy, Liana; Temido Ferreira, Mariana; Marques-Morgado, Inês; Fernandes Gomes, Bárbara; Matthiesen, Rune; Lopes, Luisa V.; Florindo, Pedro R.; Gomes, Ricardo A.; Gomes-Alves, Patrícia; Coelho, Joana E; Outeiro, Tiago; Vicente Miranda, Hugo

Alpha-synuclein (aSyn) is a central player in the pathogenesis of synucleinopathies due to its accumulation in typical protein aggregates in the brain. However, it is still unclear how it contributes to neurodegeneration. Type-2 diabetes mellitus is a risk factor for Parkinson's disease (PD). Interestingly, a common molecular alteration among these disorders is the age-associated increase in protein glycation. We hypothesized that glycation-induced neuronal dysfunction is a contributing factor in synucleinopathies. Here, we dissected the impact of methylglyoxal (MGO, a glycating agent) in mice overexpressing aSyn in the brain. We found that MGO-glycation potentiates motor, cognitive, olfactory, and colonic dysfunction in aSyn transgenic (Thy1-aSyn) mice that received a single dose of MGO via intracerebroventricular injection. aSyn accumulates in the midbrain, striatum, and prefrontal cortex, and protein glycation is increased in the cerebellum and midbrain. SWATH mass spectrometry analysis, used to quantify changes in the brain proteome, revealed that MGO mainly increase glutamatergic-associated proteins in the midbrain (NMDA, AMPA, glutaminase, VGLUT and EAAT1), but not in the prefrontal cortex, where it mainly affects the electron transport chain. The glycated proteins in the midbrain of MGO-injected Thy1-aSyn mice strongly correlate with PD and dopaminergic pathways. Overall, we demonstrated that MGO-induced glycation accelerates PD-like sensorimotor and cognitive alterations and suggest that the increase of glutamatergic signaling may underly these events. Our study sheds new light into the enhanced vulnerability of the midbrain in PD-related synaptic dysfunction and suggests that glycation suppressors and anti-glutamatergic drugs may hold promise as disease-modifying therapies for synucleinopathies.

2022Journal article

Open access

Glycation potentiates α-synuclein-associated neurodegeneration in synucleinopathies

Publication . Miranda, Hugo Vicente; Szego, Éva M.; Oliveira, Luís M. A.; Breda, Carlo; Darendelioglu, Ekrem; Oliveira, Rita M. de; Ferreira, Diana G.; Gomes, Marcos A.; Rott, Ruth; Oliveira, Márcia; Munari, Francesca; Enguita, Francisco J.; Simões, Tânia; Rodrigues, Eva F.; Heinrich, Michael; Martins, Ivo C.; Zamolo, Irina; Riess, Olaf; Cordeiro, Carlos; Freire, Ana Ponces; Lashuel, Hilal A.; Santos, Nuno C.; Lopes, Luisa V.; Xiang, Wei; Jovin, Thomas M.; Penque, Deborah; Engelender, Simone; Zweckstetter, Markus; Klucken, Jochen; Giorgini, Flaviano; Quintas, Alexandre; Outeiro, Tiago F.

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

2017Journal article

Restricted access

Posttranslational modifications of blood-derived alpha-synuclein as biochemical markers for Parkinson’s disease

Publication . Vicente Miranda, Hugo; Cassio, Rafaela; Correia Guedes, Leonor; Gomes, Marcos António; Chegão, Ana; Miranda, Elisa; Soares, Tiago; Coelho, Miguel; Rosa, Mário Miguel; Ferreira, Joaquim J; Outeiro, Tiago

Parkinson's disease (PD) is a progressive neurodegenerative disorder known for the typical motor features associated. Pathologically, it is characterized by the intracellular accumulation of alpha-synuclein (aSyn) in Lewy bodies and Lewy neurites. Currently, there are no established biochemical markers for diagnosing or for following disease progression, a major limitation for the clinical practice. Posttranslational modifications (PTMs) in aSyn have been identified and implicated on its pathobiology. Since aSyn is abundant in blood erythrocytes, we aimed to evaluate whether PTMs of aSyn in the blood might hold value as a biomarker for PD. We examined 58 patients with PD and 30 healthy age-matched individuals. We found that the levels of Y125 phosphorylated, Y39 nitrated, and glycated aSyn were increased in PD, while those of SUMO were reduced. A combinatory analysis of the levels of these PTMs resulted in an increased sensitivity, with an area under curve (AUC) of 0.843 for PD versus healthy controls, and correlated with disease severity and duration. We conclude that the levels of these selected PTMs hold strong potential as biochemical markers for PD. Ultimately, our findings might facilitate the monitoring of disease progression in clinical trials, opening the possibility for developing more effective therapies against PD.

2017Journal article

Open access

The neuroprotective action of amidated-kyotorphin on amyloid β peptide-induced Alzheimer’s disease pathophysiology

Publication . Belo, Rita F.; Martins, Margarida L. F.; Shvachiy, Liana; Costa-Coelho, Tiago; de Almeida-Borlido, Carolina; Fonseca-Gomes, João; Neves, Vera; Vicente Miranda, Hugo; Outeiro, Tiago F.; Coelho, Joana E; Xapelli, Sara; Valente, Cláudia A.; Heras, Montserrat; Bardaji, Eduard; Castanho, Miguel A. R. B.; Diógenes, Maria José; Sebastião, Ana M

Kyotorphin (KTP, l-tyrosyl-l-arginine) is an endogenous dipeptide initially described to have analgesic properties. Recently, KTP was suggested to be an endogenous neuroprotective agent, namely for Alzheimer's disease (AD). In fact, KTP levels were shown to be decreased in the cerebrospinal fluid of patients with AD, and recent data showed that intracerebroventricular (i.c.v.) injection of KTP ameliorates memory impairments in a sporadic rat model of AD. However, this administration route is far from being a suitable therapeutic strategy. Here, we evaluated if the blood-brain permeant KTP-derivative, KTP-NH2, when systemically administered, would be effective in preventing memory deficits in a sporadic AD animal model and if so, which would be the synaptic correlates of that action. The sporadic AD model was induced in male Wistar rats through i.c.v. injection of amyloid β peptide (Aβ). Animals were treated for 20 days with KTP-NH2 (32.3 mg/kg, intraperitoneally (i.p.), starting at day 3 after Aβ administration) before memory testing (Novel object recognition (NOR) and Y-maze (YM) tests). Animals were then sacrificed, and markers for gliosis were assessed by immunohistochemistry and Western blot analysis. Synaptic correlates were assessed by evaluating theta-burst induced long term potentiation (LTP) of field excitatory synaptic potentials (fEPSPs) recorded from hippocampal slices and cortical spine density analysis. In the absence of KTP-NH2 treatment, Aβ-injected rats had clear memory deficits, as assessed through NOR or YM tests. Importantly, these memory deficits were absent in Aβ-injected rats that had been treated with KTP-NH2, which scored in memory tests as control (sham i.c.v. injected) rats. No signs of gliosis could be detected at the end of the treatment in any group of animals. LTP magnitude was significantly impaired in hippocampal slices that had been incubated with Aβ oligomers (200 nM) in the absence of KTP-NH2. Co-incubation with KTP-NH2 (50 nM) rescued LTP toward control values. Similarly, Aβ caused a significant decrease in spine density in cortical neuronal cultures, and this was prevented by co-incubation with KTP-NH2 (50 nM). In conclusion, the present data demonstrate that i.p. KTP-NH2 treatment counteracts Aβ-induced memory impairments in an AD sporadic model, possibly through the rescuing of synaptic plasticity mechanisms.

2020Journal article

Open access