Examinando por Autor "Wyneken, Ursula"
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Ítem Epigenetic editing of the Dlg4/PSD95 gene improves cognition in aged and Alzheimer's disease mice(BRAIA, 2017-12) Bustos, Fernando J.; Ampuero, Estibaliz; Jury, Nur; Aguilar, Rodrigo; Falahi, Fahimeh; Toledo, Jorge; Ahumada, Juan; Lata, Jaclyn; Cubillos, Paula; Henríquez, Berta; Guerra, Miguel V.; Stehberg, Jimmy; Neve, Rachael L.; Inestrosa, Nibaldo C.; Wyneken, Ursula; Fuenzalida, Marco; Härtel, Steffen; Sena-Esteves, Miguel; Varela-Nallar, Lorena; Rots, Marianne G.; Montecino, Martin; Van Zundert, BrigitteThe Dlg4 gene encodes for post-synaptic density protein 95 (PSD95), a major synaptic protein that clusters glutamate receptors and is critical for plasticity. PSD95 levels are diminished in ageing and neurodegenerative disorders, including Alzheimer's disease and Huntington's disease. The epigenetic mechanisms that (dys)regulate transcription of Dlg4/PSD95, or other plasticity genes, are largely unknown, limiting the development of targeted epigenome therapy. We analysed the Dlg4/PSD95 epigenetic landscape in hippocampal tissue and designed a Dlg4/PSD95 gene-targeting strategy: a Dlg4/PSD95 zinc finger DNA-binding domain was engineered and fused to effector domains to either repress (G9a, Suvdel76, SKD) or activate (VP64) transcription, generating artificial transcription factors or epigenetic editors (methylating H3K9). These epi-editors altered critical histone marks and subsequently Dlg4/PSD95 expression, which, importantly, impacted several hippocampal neuron plasticity processes. Intriguingly, transduction of the artificial transcription factor PSD95-VP64 rescued memory deficits in aged and Alzheimer's disease mice. Conclusively, this work validates PSD95 as a key player in memory and establishes epigenetic editing as a potential therapy to treat human neurological disorders. © 2017 The Author. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved.Ítem Neuronal surface P antigen (NSPA) modulates postsynaptic NMDAR stability through ubiquitination of tyrosine phosphatase PTPMEG(BioMed Central Ltd, 2020-12-01) Espinoza, Sofía; Arredondo, Sebastián B.; Barake, Francisca; Carvajal, Francisco; Guerrero, Fernanda G.; Segovia-Miranda, Fabian; Valenzuela, David M.; Wyneken, Ursula; Rojas-Fernández, Alejandro; Cerpa, Waldo; Massardo, Loreto; Varela-Nallar, Lorena; González, AlfonsoBackground: Cognitive dysfunction (CD) is common among patients with the autoimmune disease systemic lupus erythematosus (SLE). Anti-ribosomal P autoantibodies associate with this dysfunction and have neuropathogenic effects that are mediated by cross-reacting with neuronal surface P antigen (NSPA) protein. Elucidating the function of NSPA can then reveal CD pathogenic mechanisms and treatment opportunities. In the brain, NSPA somehow contributes to glutamatergic NMDA receptor (NMDAR) activity in synaptic plasticity and memory. Here we analyze the consequences of NSPA absence in KO mice considering its structural features shared with E3 ubiquitin ligases and the crucial role of ubiquitination in synaptic plasticity. Results: Electrophysiological studies revealed a decreased long-term potentiation in CA3-CA1 and medial perforant pathway-dentate gyrus (MPP-DG) hippocampal circuits, reflecting glutamatergic synaptic plasticity impairment in NSPA-KO mice. The hippocampal dentate gyrus of these mice showed a lower number of Arc-positive cells indicative of decreased synaptic activity and also showed proliferation defects of neural progenitors underlying less adult neurogenesis. All this translates into poor spatial and recognition memory when NSPA is absent. A cell-based assay demonstrated ubiquitination of NSPA as a property of RBR-type E3 ligases, while biochemical analysis of synaptic regions disclosed the tyrosine phosphatase PTPMEG as a potential substrate. Mice lacking NSPA have increased levels of PTPMEG due to its reduced ubiquitination and proteasomal degradation, which correlated with lower levels of GluN2A and GluN2B NMDAR subunits only at postsynaptic densities (PSDs), indicating selective trafficking of these proteins out of PSDs. As both GluN2A and GluN2B interact with PTPMEG, tyrosine (Tyr) dephosphorylation likely drives their endocytic removal from the PSD. Actually, immunoblot analysis showed reduced phosphorylation of the GluN2B endocytic signal Tyr1472 in NSPA-KO mice. Conclusions: NSPA contributes to hippocampal plasticity and memory processes ensuring appropriate levels of adult neurogenesis and PSD-located NMDAR. PTPMEG qualifies as NSPA ubiquitination substrate that regulates Tyr phosphorylation-dependent NMDAR stability at PSDs. The NSPA/PTPMEG pathway emerges as a new regulator of glutamatergic transmission and plasticity and may provide mechanistic clues and therapeutic opportunities for anti-P-mediated pathogenicity in SLE, a still unmet need. © 2020, The Author(s).Ítem Two chronic stress models based on movement restriction in rats respond selectively to antidepressant drugs: Aldolase C as a potential biomarker(International Journal of Neuropsychopharmacology Volume 18, Issue 10September 2015, 2015-09) Ampuero, Estibaliz; Luarte, Alejandro; Santibañez, Marcos; Varas-Godoy, Manuel; Toledo, Jorge; Diaz-Veliz, Gabriela; Cavada, Gabriel; Javier Rubio, F.; Wyneken, UrsulaBackground: Clinically depressed individuals respond to different types of antidepressants, suggesting that different neurobiological mechanisms may be responsible for their depression. However, animal models to characterize this are not yet available. Methods: We induced depressive-like behaviors in rats using 2 different chronic stress models: restraint in small cages or immobilization in adaptable plastic cones. Both models increased anxiety responses evaluated by novelty-suppressed feeding and the elevated plus-maze; increased learned helplessness evaluated by the tail suspension and forced swimming tests; and increased anhedonia evaluated by the sucrose preference test. Results: We assessed the ability of 2 different types of antidepressants to ameliorate depressive-like behaviors. We administered the serotonin reuptake inhibitor fluoxetine or the noradrenaline reuptake inhibitor reboxetine once daily for 28 days to rats that received either chronic restraint or immobilization stress, or no stress. Behavioral analysis revealed that fluoxetine ameliorated depressive-like behaviors when induced by chronic restraint stress, whereas reboxetine ameliorated these behaviors when induced by chronic immobilization stress. To further test biological differences between both models, we evaluated the levels of Aldolase C, an enzyme expressed by forebrain astrocytes that is regulated by antidepressant treatment, in the cerebrospinal fluid: chronic restraint stress, but not immobilization stress, increased the levels of Aldolase C. Moreover, the presence of astrocyte-derived Aldolase C-GFP in the cerebrospinal fluid indicates its central origin. Conclusions: Two stress paradigms induced depressive-like behaviors that were sensitive to different antidepressant treatments. Biomarkers such as Aldolase C could help determine optimal antidepressant treatments for clinically depressed patients. © 2015 The Author.