Publications by authors named "Cristina Grau"

9 Publications

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Comprehensive Analysis of GABA-A1R Developmental Alterations in Rett Syndrome: Setting the Focus for Therapeutic Targets in the Time Frame of the Disease.

Int J Mol Sci 2020 01 14;21(2). Epub 2020 Jan 14.

Synaptic Metabolism Lab, Neurology Department, Institut Pediàtric de Recerca, Hospital Sant Joan de Déu and CIBERER, 08950 Barcelona, Spain.

Rett syndrome, a serious neurodevelopmental disorder, has been associated with an altered expression of different synaptic-related proteins and aberrant glutamatergic and γ-aminobutyric acid (GABA)ergic neurotransmission. Despite its severity, it lacks a therapeutic option. Through this work we aimed to define the relationship between MeCP2 and GABAA.-A1 receptor expression, emphasizing the time dependence of such relationship. For this, we analyzed the expression of the ionotropic receptor subunit in different MeCP2 gene-dosage and developmental conditions, in cells lines, and in primary cultured neurons, as well as in different developmental stages of a Rett mouse model. Further, RNAseq and systems biology analysis was performed from post-mortem brain biopsies of Rett patients. We observed that the modulation of the MeCP2 expression in cellular models (both Neuro2a (N2A) cells and primary neuronal cultures) revealed a MeCP2 positive effect on the GABAA.-A1 receptor subunit expression, which did not occur in other proteins such as KCC2 (Potassium-chloride channel, member 5). In the Mecp2+/- mouse brain, both the KCC2 and GABA subunits expression were developmentally regulated, with a decreased expression during the pre-symptomatic stage, while the expression was variable in the adult symptomatic mice. Finally, the expression of the gamma-aminobutyric acid (GABA) receptor-related synaptic proteins from the postmortem brain biopsies of two Rett patients was evaluated, specifically revealing the GABA A1R subunit overexpression. The identification of the molecular changes along with the Rett syndrome prodromic stages strongly endorses the importance of time frame when addressing this disease, supporting the need for a neurotransmission-targeted early therapeutic intervention.
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http://dx.doi.org/10.3390/ijms21020518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7014188PMC
January 2020

L-Serine dietary supplementation is associated with clinical improvement of loss-of-function -related pediatric encephalopathy.

Sci Signal 2019 06 18;12(586). Epub 2019 Jun 18.

Bellvitge Biomedical Research Institute (IDIBELL)-Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona 08908, Spain.

Autosomal dominant mutations in are associated with severe encephalopathy, but little is known about the pathophysiological outcomes and any potential therapeutic interventions. Genetic studies have described the association between de novo mutations of genes encoding the subunits of the -methyl-d-aspartate receptor (NMDAR) and severe neurological conditions. Here, we evaluated a missense mutation in , causing a proline-to-threonine switch (P553T) in the GluN2B subunit of NMDAR, which was found in a 5-year-old patient with Rett-like syndrome with severe encephalopathy. Structural molecular modeling predicted a reduced pore size of the mutant GluN2B-containing NMDARs. Electrophysiological recordings in a HEK-293T cell line expressing the mutated subunit confirmed this prediction and showed an associated reduced glutamate affinity. Moreover, GluN2B(P553T)-expressing primary murine hippocampal neurons showed decreased spine density, concomitant with reduced NMDA-evoked currents and impaired NMDAR-dependent insertion of the AMPA receptor subunit GluA1 at stimulated synapses. Furthermore, the naturally occurring coagonist d-serine restored function to GluN2B(P553T)-containing NMDARs. l-Serine dietary supplementation of the patient was hence initiated, resulting in the increased abundance of d-serine in the plasma and brain. The patient has shown notable improvements in motor and cognitive performance and communication after 11 and 17 months of l-serine dietary supplementation. Our data suggest that l-serine supplementation might ameliorate -related severe encephalopathy and other neurological conditions caused by glutamatergic signaling deficiency.
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http://dx.doi.org/10.1126/scisignal.aaw0936DOI Listing
June 2019

Phosphoproteomic Alterations of Ionotropic Glutamate Receptors in the Hippocampus of the Ts65Dn Mouse Model of Down Syndrome.

Front Mol Neurosci 2018 25;11:226. Epub 2018 Jul 25.

Neuropharmacology Unit, Bellvitge Biomedical Research Institute (IDIBELL)-University of Barcelona, Barcelona, Spain.

Down syndrome (DS), the main genetic cause of intellectual disability, is associated with an imbalance of excitatory/inhibitory neurotransmitter systems. The phenotypic assessment and pharmacotherapy interventions in DS murine models strongly pointed out glutamatergic neurotransmission alterations (specially affecting ionotropic glutamate receptors [iGluRs]) that might contribute to DS pathophysiology, which is in agreement with DS condition. iGluRs play a critical role in fast-mediated excitatory transmission, a process underlying synaptic plasticity. Neuronal plasticity is biochemically modulated by post-translational modifications, allowing rapid and reversible adaptation of synaptic strength. Among these modifications, phosphorylation/dephosphorylation processes strongly dictate iGluR protein-protein interactions, cell surface trafficking, and subsynaptic mobility. Hence, we hypothesized that dysregulation of phosphorylation/dephosphorylation balance might affect neuronal function, which in turn could contribute to the glutamatergic neurotransmitter alterations observed in DS. To address this point, we biochemically purified subsynaptic hippocampal fractions from adult Ts65Dn mice, a trisomic mouse model recapitulating DS phenotypic alterations. Proteomic analysis showed significant alterations of the molecular composition of subsynaptic compartments of hippocampal trisomic neurons. Further, we characterized iGluR phosphopattern in the hippocampal glutamatergic synapse of trisomic mice. Phosphoenrichment-coupled mass spectrometry analysis revealed specific subsynaptic- and trisomy-associated iGluR phosphorylation signature, concomitant with differential subsynaptic kinase and phosphatase composition of Ts65Dn hippocampal subsynaptic compartments. Furthermore, biochemical data were used to build up a genotype-kinome-iGluR phosphopattern matrix in the different subsynaptic compartments. Overall, our results provide a precise profile of iGluR phosphopattern alterations in the glutamatergic synapse of the Ts65Dn mouse model and support their contribution to DS-associated synaptopathy. The alteration of iGluR phosphoresidues in Ts65Dn hippocampi, together with the kinase/phosphatase signature, identifies potential novel therapeutic targets for the treatment of glutamatergic dysfunctions in DS.
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http://dx.doi.org/10.3389/fnmol.2018.00226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6095006PMC
July 2018

Rett-like Severe Encephalopathy Caused by a De Novo GRIN2B Mutation Is Attenuated by D-serine Dietary Supplement.

Biol Psychiatry 2018 Jan 16;83(2):160-172. Epub 2017 Jun 16.

Bellvitge Biomedical Research Institute-Unit of Neuropharmacology and Pain Group, University of Barcelona, Barcelona, Spain. Electronic address:

Background: N-Methyl-D-aspartate receptors (NMDARs) play pivotal roles in synaptic development, plasticity, neural survival, and cognition. Despite recent reports describing the genetic association between de novo mutations of NMDAR subunits and severe psychiatric diseases, little is known about their pathogenic mechanisms and potential therapeutic interventions. Here we report a case study of a 4-year-old Rett-like patient with severe encephalopathy carrying a missense de novo mutation in GRIN2B(p.P553T) coding for the GluN2B subunit of NMDAR.

Methods: We generated a dynamic molecular model of mutant GluN2B-containing NMDARs. We expressed the mutation in cell lines and primary cultures, and we evaluated the putative morphological, electrophysiological, and synaptic plasticity alterations. Finally, we evaluated D-serine administration as a therapeutic strategy and translated it to the clinical practice.

Results: Structural molecular modeling predicted a reduced pore size of mutant NMDARs. Electrophysiological recordings confirmed this prediction and also showed gating alterations, a reduced glutamate affinity associated with a strong decrease of NMDA-evoked currents. Moreover, GluN2B(P553T)-expressing neurons showed decreased spine density, concomitant with reduced NMDA-evoked currents and impaired NMDAR-dependent insertion of GluA1 at stimulated synapses. Notably, the naturally occurring coagonist D-serine was able to attenuate hypofunction of GluN2B(p.P553T)-containing NMDARs. Hence, D-serine dietary supplementation was initiated. Importantly, the patient has shown remarkable motor, cognitive, and communication improvements after 17 months of D-serine dietary supplementation.

Conclusions: Our data suggest that hypofunctional NMDARs containing GluN2B(p.P553T) can contribute to Rett-like encephalopathy and that their potentiation by D-serine treatment may underlie the associated clinical improvement.
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http://dx.doi.org/10.1016/j.biopsych.2017.05.028DOI Listing
January 2018

Linear Unilateral Basaloid Follicular Hamartoma Following Blaschko's Lines: Two Case Reports and Review of the Literature.

Pediatr Dermatol 2017 Jul 29;34(4):e196-e200. Epub 2017 Jun 29.

Department of Dermatology, Complejo Hospitalario Insular Materno Infantil de Gran Canaria, Las Palmas, Spain.

Basaloid follicular hamartoma (BFH) is a rare follicular malformation characterized by variable clinical presentations and identical histopathologic features. We present the cases of a 3-month-old boy and an 8-year-old boy with linear unilateral BFH. To the best of our knowledge, only 14 cases of linear unilateral BFH have been described in the English-language literature.
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http://dx.doi.org/10.1111/pde.13185DOI Listing
July 2017

Fixed sunlight eruption: a new idiopathic photodermatosis rather than a variant of fixed drug eruption.

Photodermatol Photoimmunol Photomed 2017 07 26;33(4):222-224. Epub 2017 Apr 26.

Dermatology Department, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.

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http://dx.doi.org/10.1111/phpp.12309DOI Listing
July 2017

Glutamatergic stimulation induces GluN2B translation by the nitric oxide-Heme-Regulated eIF2α kinase in cortical neurons.

Oncotarget 2016 09;7(37):58876-58892

Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.

The activation of N-Methyl D-Aspartate Receptor (NMDAR) by glutamate is crucial in the nervous system function, particularly in memory and learning. NMDAR is composed by two GluN1 and two GluN2 subunits. GluN2B has been reported to participate in the prevalent NMDAR subtype at synapses, the GluN1/2A/2B. Here we studied the regulation of GluN2B expression in cortical neurons finding that glutamate up-regulates GluN2B translation through the action of nitric oxide (NO), which induces the phosphorylation of the eukaryotic translation initiation factor 2 α (eIF2α). It is a process mediated by the NO-heme-regulated eIF2α kinase (HRI), as the effect was avoided when a specific HRI inhibitor or a HRI small interfering RNA (siHRI) were used. We found that the expressed GluN2B co-localizes with PSD-95 at the postsynaptic ending, which strengthen the physiological relevance of the proposed mechanism. Moreover the receptors bearing GluN2B subunits upon NO stimulation are functional as high Ca2+ entry was measured and increases the co-localization between GluN2B and GluN1 subunits. In addition, the injection of the specific HRI inhibitor in mice produces a decrease in memory retrieval as tested by the Novel Object Recognition performance. Summarizing our data suggests that glutamatergic stimulation induces HRI activation by NO to trigger GluN2B expression and this process would be relevant to maintain postsynaptic activity in cortical neurons.
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http://dx.doi.org/10.18632/oncotarget.11417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5312282PMC
September 2016

DYRK1A-mediated phosphorylation of GluN2A at Ser(1048) regulates the surface expression and channel activity of GluN1/GluN2A receptors.

Front Cell Neurosci 2014 17;8:331. Epub 2014 Oct 17.

Institute of Neuropathology, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat Barcelona, Spain.

N-methyl-D-aspartate glutamate receptors (NMDARs) play a pivotal role in neural development and synaptic plasticity, as well as in neurological disease. Since NMDARs exert their function at the cell surface, their density in the plasma membrane is finely tuned by a plethora of molecules that regulate their production, trafficking, docking and internalization in response to external stimuli. In addition to transcriptional regulation, the density of NMDARs is also influenced by post-translational mechanisms like phosphorylation, a modification that also affects their biophysical properties. We previously described the increased surface expression of GluN1/GluN2A receptors in transgenic mice overexpressing the Dual specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A), suggesting that DYRK1A regulates NMDARs. Here we have further investigated whether the density and activity of NMDARs were modulated by DYRK1A phosphorylation. Accordingly, we show that endogenous DYRK1A is recruited to GluN2A-containing NMDARs in the adult mouse brain, and we identify a DYRK1A phosphorylation site at Ser(1048) of GluN2A, within its intracellular C-terminal domain. Mechanistically, the DYRK1A-dependent phosphorylation of GluN2A at Ser(1048) hinders the internalization of GluN1/GluN2A, causing an increase of surface GluN1/GluN2A in heterologous systems, as well as in primary cortical neurons. Furthermore, GluN2A phosphorylation at Ser(1048) increases the current density and potentiates the gating of GluN1/GluN2A receptors. We conclude that DYRK1A is a direct regulator of NMDA receptors and we propose a novel mechanism for the control of NMDAR activity in neurons.
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http://dx.doi.org/10.3389/fncel.2014.00331DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4201086PMC
November 2014

Use of PC12 cells and rat superior cervical ganglion sympathetic neurons as models for neuroprotective assays relevant to Parkinson's disease.

Methods Mol Biol 2012 ;846:201-11

Department of Pharmacology, University of Barcelona, Barcelona, Spain.

Cellular models composed of primary neuronal cultures or neuron-like cell lines are commonly used to study neuron cell death and to test the neuroprotective properties of specific compounds. Cellular models are easily accessible, permitting dissection and modulation of signaling pathways involved in neuron death. For example, drug or shRNA delivery is more straightforward since there is no blood-brain barrier to cross. However, since these models have their limitations, any important findings should ultimately be verified with animal models and human samples. Here, we describe two cellular models that can be used as a highly informative and easy to use starting point for testing potential neuroprotective drugs for Parkinson's disease: PC12 cells and sympathetic neuronal cell cultures. We describe in detail the protocols needed to apply these models to study neuroprotection in the context of Parkinson's disease.
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http://dx.doi.org/10.1007/978-1-61779-536-7_18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3678375PMC
June 2012