Open Access
Astrocytic GLUT1 reduction paradoxically improves central and peripheral glucose homeostasis
(American Association for the Advancement of Science, 2024-10-18) Ardanaz, Carlos G.; Cruz, Aida de la; Minhas, Paras S.; Hernández-Martín, Nira; Pozo, Miguel Ángel ; Valdecantos, M. Pilar; Martínez Valverde, Ángela; Villa-Valverde, Palmira; Elizalde-Horcada, Marcos; Puerta, Elena; Ramírez, María J.; Ortega, Jorge E.; Urbiola, Ainhoa; Ederra, Cristina; Ariz Galilea, Mikel; Ortiz de Solórzano, Carlos; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Karsenty, Gerard; Brüning, Jens C. ; Solas, Maite; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
Astrocytes are considered an essential source of blood-borne glucose or its metabolites to neurons. Nonetheless, the necessity of the main astrocyte glucose transporter, i.e., GLUT1, for brain glucose metabolism has not been defined. Unexpectedly, we found that brain glucose metabolism was paradoxically augmented in mice with astrocytic GLUT1 reduction (GLUT1ΔGFAP mice). These mice also exhibited improved peripheral glucose metabolism especially in obesity, rendering them metabolically healthier. Mechanistically, we observed that GLUT1-deficient astrocytes exhibited increased insulin receptor–dependent ATP release, and that both astrocyte insulin signaling and brain purinergic signaling are essential for improved brain function and systemic glucose metabolism. Collectively, we demonstrate that astrocytic GLUT1 is central to the regulation of brain energetics, yet its depletion triggers a reprogramming of brain metabolism sufficient to sustain energy requirements, peripheral glucose homeostasis, and cognitive function.
Open Access
Host tau genotype specifically designs and regulates tau seeding and spreading and host tau transformation following intrahippocampal injection of identical tau AD inoculum
(MDPI, 2022) Andrés Benito, Pol; Carmona, Margarita; Jordán, Mónica; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Río, José Antonio del; Ferrer, Isidro; Ciencias de la Salud; Osasun Zientziak
Several studies have demonstrated the different characteristics of tau seeding and spreading following intracerebral inoculation in murine models of tau-enriched fractions of brain homogenates from AD and other tauopathies. The present study is centered on the importance of host tau in tau seeding and the molecular changes associated with the transformation of host tau into abnormal tau. The brains of three adult murine genotypes expressing different forms of tau—WT (murine 4Rtau), hTau (homozygous transgenic mice knock-out for murine tau protein and heterozygous expressing human forms of 3Rtau and 4Rtau proteins), and mtWT (homozygous transgenic mice knock-out for murine tau protein)—were analyzed following unilateral hippocampal inoculation of sarkosyl-insoluble tau fractions from the same AD and control cases. The present study reveals that (a) host tau is mandatory for tau seeding and spreading following tau inoculation from sarkosyl-insoluble fractions obtained from AD brains; (b) tau seeding does not occur following intracerebral inoculation of sarkosyl-insoluble fractions from controls; (c) tau seeding and spreading are characterized by variable genotype-dependent tau phosphorylation and tau nitration, MAP2 phosphorylation, and variable activation of kinases that co-localize with abnormal tau deposits; (d) transformation of host tau into abnormal tau is an active process associated with the activation of specific kinases; (e) tau seeding is accompanied by modifications in tau splicing, resulting in the expression of new 3Rtau and 4Rtau isoforms, thus indicating that inoculated tau seeds have the capacity to model exon 10 splicing of the host mapt or MAPT with a genotype-dependent pattern; (e) selective regional and cellular vulnerabilities, and different molecular compositions of the deposits, are dependent on the host tau of mice injected with identical AD tau inocula.
Open Access
Network-driven proteogenomics unveils an aging-related imbalance in the olfactory IκBα-NFκB p65 complex functionality in Tg2576 Alzheimer’s disease mouse model
(MDPI, 2017) Palomino Alonso, Maialen; Lachén Montes, Mercedes; González Morales, Andrea; Ausín, Karina; Pérez Mediavilla, Alberto; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Ciencias de la Salud; Osasun Zientziak; Gobierno de Navarra / Nafarroako Gobernua, PC023-24; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Olfaction is often deregulated in Alzheimer’s disease (AD) patients, and is also impaired in transgenic Tg2576 AD mice, which overexpress the Swedish mutated form of human amyloid precursor protein (APP). However, little is known about the molecular mechanisms that accompany the neurodegeneration of olfactory structures in aged Tg2576 mice. For that, we have applied proteome- and transcriptome-wide approaches to probe molecular disturbances in the olfactory bulb (OB) dissected from aged Tg2576 mice (18 months of age) as compared to those of age matched wild-type (WT) littermates. Some over-represented biological functions were directly relevant to neuronal homeostasis and processes of learning, cognition, and behavior. In addition to the modulation of CAMP responsive element binding protein 1 (CREB1) and APP interactomes, an imbalance in the functionality of the IκBα-NFκB p65 complex was observed during the aging process in the OB of Tg2576 mice. At two months of age, the phosphorylated isoforms of olfactory IκBα and NFκB p65 were inversely regulated in transgenic mice. However, both phosphorylated proteins were increased at 6 months of age, while a specific drop in IκBα levels was detected in 18-month-old Tg2576 mice, suggesting a transient activation of NFκB in the OB of Tg2576 mice. Taken together, our data provide a metabolic map of olfactory alterations in aged Tg2576 mice, reflecting the progressive effect of APP overproduction and β-amyloid (Aβ) accumulation on the OB homeostasis in aged stages.
Open Access
Pyk2 regulates MAMs and mitochondrial dynamics in hippocampal neurons
(MDPI, 2022) López-Molina, Laura; Fernández Irigoyen, Joaquín; Cifuentes-Díaz, Carmen; Alberch, Jordi; Girault, Jean Antoine; Santamaría Martínez, Enrique; Ginés, Silvia; Giralt, Albert; Ciencias de la Salud; Osasun Zientziak
Pyk2 is a non-receptor tyrosine kinase enriched in hippocampal neurons, which can be activated by calcium-dependent mechanisms. In neurons, Pyk2 is mostly localised in the cytosol and dendritic shafts but can translocate to spines and/or to the nucleus. Here, we explore the function of a new localisation of Pyk2 in mitochondria-associated membranes (MAMs), a subdomain of ER-mitochondria surface that acts as a signalling hub in calcium regulation. To test the role of Pyk2 in MAMs’ calcium transport, we used full Pyk2 knockout mice (Pyk2−/−) for in vivo and in vitro studies. Here we report that Pyk2−/− hippocampal neurons present increased ER-mitochondrial contacts along with defective calcium homeostasis. We also show how the absence of Pyk2 modulates mitochondrial dynamics and morphology. Taken all together, our results point out that Pyk2 could be highly relevant in the modulation of ER-mitochondria calcium efflux, affecting in turn mitochondrial function
Open Access
Oleuropein-driven reprogramming of the myeloid cell compartment to sensitise tumours to PD-1/PD-L1 blockade strategies
(Springer Nature, 2024) Blanco, Ester; Silva-Pilipich, Noelia; Bocanegra Gondán, Ana Isabel; Chocarro de Erauso, Luisa; Procopio, Antonio; Ausín, Karina; Fernández Irigoyen, Joaquín; Fernández Rubio, Leticia; Razquin, Nerea; Igea, Ana; Garnica, Maider; Echaide Górriz, Míriam; Arasanz Esteban, Hugo; Vera García, Ruth; Escors Murugarren, David; Smerdou, Cristian; Kochan, Grazyna; Ciencias de la Salud; Osasun Zientziak
Background: Previous studies have shown that functional systemic immunity is required for the efficacy of PD-1/PD-L1 blockade immunotherapies in cancer. Hence, systemic reprogramming of immunosuppressive dysfunctional myeloid cells could overcome resistance to cancer immunotherapy. Methods: Reprogramming of tumour-associated myeloid cells with oleuropein was studied by quantitative differential proteomics, phenotypic and functional assays in mice and lung cancer patients. Combinations of oleuropein and two different delivery methods of anti-PD-1 antibodies were tested in colorectal cancer tumour models and in immunotherapy-resistant lung cancer models. Results: Oleuropein treatment reprogrammed monocytic and granulocytic myeloid-derived suppressor cells, and tumour-associated macrophages towards differentiation of immunostimulatory subsets. Oleuropein regulated major differentiation programmes associated to immune modulation in myeloid cells, which potentiated T cell responses and PD-1 blockade. PD-1 antibodies were delivered by two different strategies, either systemically or expressed within tumours using a self-amplifying RNA vector. Combination anti-PD-1 therapies with oleuropein increased tumour infiltration by immunostimulatory dendritic cells in draining lymph nodes, leading to systemic antitumour T cell responses. Potent therapeutic activities were achieved in colon cancer and lung cancer models resistant to immunotherapies, even leading to complete tumour regression. Discussion: Oleuropein significantly improves the outcome of PD-1/PD-L1 blockade immunotherapy strategies by reprogramming myeloid cells.
Open Access
Involvement of glucosamine 6 phosphate isomerase 2 (GNPDA2) overproduction in beta-amyloid- and Tau P301L-driven pathomechanisms
(MDPI, 2024) Lachén Montes, Mercedes; Cartas Cejudo, Paz; Cortés, Adriana; Anaya-Cubero, Elena; Peral, Erika; Ausín, Karina; Díaz-Peña, Ramón; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Ciencias de la Salud; Osasun Zientziak
Alzheimer’s disease (AD) is a neurodegenerative olfactory disorder affecting millions of people worldwide. Alterations in the hexosamine- or glucose-related pathways have been described through AD progression. Specifically, an alteration in glucosamine 6 phosphate isomerase 2 (GNPDA2) protein levels has been observed in olfactory areas of AD subjects. However, the biological role of GNPDA2 in neurodegeneration remains unknown. Using mass spectrometry, multiple GNPDA2 interactors were identified in human nasal epithelial cells (NECs) mainly involved in intraciliary transport. Moreover, GNPDA2 overexpression induced an increment in NEC proliferation rates, accompanied by transcriptomic alterations in Type II interferon signaling or cellular stress responses. In contrast, the presence of beta-amyloid or mutated Tau-P301L in GNPDA2-overexpressing NECs induced a slowdown in the proliferative capacity in parallel with a disruption in protein processing. The proteomic characterization of Tau-P301L transgenic zebrafish embryos demonstrated that GNPDA2 overexpression interfered with collagen biosynthesis and RNA/protein processing, without inducing additional changes in axonal outgrowth defects or neuronal cell death. In humans, a significant increase in serum GNPDA2 levels was observed across multiple neurological proteinopathies (AD, Lewy body dementia, progressive supranuclear palsy, mixed dementia and amyotrophic lateral sclerosis) (n = 215). These data shed new light on GNPDA2-dependent mechanisms associated with the neurodegenerative process beyond the hexosamine route.
Open Access
Familial globular glial tauopathy linked to MAPT mutations: molecular neuropathology and seeding capacity of a prototypical mixed neuronal and glial tauopathy
(Springer, 2020) Ferrer, Isidro; Andrés Benito, Pol; Zelaya Huerta, María Victoria; Erro Aguirre, María Elena; Carmona, Margarita; Ausín, Karina; Lachén Montes, Mercedes; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Río, José Antonio del; Ciencias de la Salud; Osasun Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Globular glial tauopathy (GGT) is a progressive neurodegenerative disease involving the grey matter and white matter (WM) and characterized by neuronal deposition of hyper-phosphorylated, abnormally conformed, truncated, oligomeric 4Rtau in neurons and in glial cells forming typical globular astrocyte and oligodendrocyte inclusions (GAIs and GOIs, respectively) and coiled bodies. Present studies centre on four genetic GGT cases from two unrelated families bearing the P301T mutation in MAPT and one case of sporadic GGT (sGGT) and one case of GGT linked to MAPT K317M mutation, for comparative purposes. Clinical and neuropathological manifestations and biochemical profiles of phospho-tau are subjected to individual variations in patients carrying the same mutation, even in carriers of the same family, independently of the age of onset, gender, and duration of the disease. Immunohistochemistry, western blotting, transcriptomic, proteomics and phosphoproteomics, and intra-cerebral inoculation of brain homogenates to wild-type (WT) mice were the methods employed. In GGT cases linked to MAPT P301T mutation, astrocyte markers GFAP, ALDH1L1, YKL40 mRNA and protein, GJA1 mRNA, and AQ4 protein are significantly increased; glutamate transporter GLT1 (EAAT2) and glucose transporter (SLC2A1) decreased; mitochondrial pyruvate carrier 1 (MPC1) increased, and mitochondrial uncoupling protein 5 (UCP5) almost absent in GAIs in frontal cortex (FC). Expression of oligodendrocyte markers OLIG1 and OLIG2mRNA, and myelin-related genes MBP, PLP1, CNP, MAG, MAL, MOG, and MOBP are significantly decreased in WM; CNPase, PLP1, and MBP antibodies reveal reduction and disruption of myelinated fibres; and SMI31 antibodies mark axonal damage in the WM. Altered expression of AQ4, GLUC-t, and GLT-1 is also observed in sGGT and in GGT linked to MAPT K317M mutation. These alterations point to primary astrogliopathy and oligodendrogliopathy in GGT. In addition, GGT linked to MAPT P301T mutation proteotypes unveil a proteostatic imbalance due to widespread (phospho)proteomic dearrangement in the FC and WM, triggering a disruption of neuron projection morphogenesis and synaptic transmission. Identification of hyper-phosphorylation of variegated proteins calls into question the concept of phospho-tau-only alteration in the pathogenesis of GGT. Finally, unilateral inoculation of sarkosyl-insoluble fractions of GGT homogenates from GGT linked to MAPT P301T, sGGT, and GGT linked to MAPT K317M mutation in the hippocampus, corpus callosum, or caudate/putamen in wild-type mice produces seeding, and time- and region-dependent spreading of phosphorylated, non-oligomeric, and non-truncated 4Rtau and 3Rtau, without GAIs and GOIs but only of coiled bodies. These experiments prove that host tau strains are important in the modulation of cellular vulnerability and phenotypes of phospho-tau aggregates.
Open Access
Alterations of the IKZF1-IKZF2 tandem in immune cells of schizophrenia patients regulate associated phenotypes
(BMC, 2024-12-18) Ballasch, Iván; López-Molina, Laura; Galán-Ganga, Marcos; Sancho-Balsells, Anna; Rodríguez-Navarro, Irene; Borràs-Pernas, Sara; Rabadán, M. Ángeles; Chen, Wanqi; Pastó-Pellicer, Carlota; Flotta, Francesca; Maoyu, Wang; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Aguilar, Ruth; Dobaño, Carlota; Egri, Natalia; Hernández, Carla; Alfonso, Miqueu; Juan, Manel; Alberch, Jordi; Toro, Daniel del; Arranz, Belén; Canals, Josep M.; Giralt, Albert; Ciencias de la Salud; Osasun Zientziak
Schizophrenia is a complex multifactorial disorder and increasing evidence suggests the involvement of immune dysregulations in its pathogenesis. We observed that IKZF1 and IKZF2, classic immune-related transcription factors (TFs), were both downregulated in patients' peripheral blood mononuclear cells (PBMCs) but not in their brain. We generated a new mutant mouse model with a reduction in Ikzf1 and Ikzf2 to study the impact of those changes. Such mice developed deficits in the three dimensions (positive-negative-cognitive) of schizophrenia-like phenotypes associated with alterations in structural synaptic plasticity. We then studied the secretomes of cultured PBMCs obtained from patients and identified potentially secreted molecules, which depended on IKZF1 and IKZF2 mRNA levels, and that in turn have an impact on neural synchrony, structural synaptic plasticity and schizophrenia-like symptoms in in vivo and in vitro models. Our results point out that IKZF1-IKZF2-dependent immune signals negatively impact on essential neural circuits involved in schizophrenia.
Open Access
Sex-specific role of galectin-3 in aortic stenosis
(BMC, 2023) Matilla Cuenca, Lara; Martín Núñez, Ernesto; Garaikoetxea Zubillaga, Mattie; Navarro, Adela; Tamayo Rodríguez, Ibai; Fernández Celis, Amaya; Gaínza Calleja, Alicia; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Muntendam, Pieter; Álvarez, Virginia; Sádaba Sagredo, Rafael; Jover, Eva; López Andrés, Natalia; Ciencias de la Salud; Osasun Zientziak; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Background: Aortic stenosis (AS) is characterized by infammation, fbrosis, osteogenesis and angiogenesis. Men and women develop these mechanisms diferently. Galectin-3 (Gal-3) is a pro-infammatory and pro-osteogenic lectin in AS. In this work, we aim to analyse a potential sex-diferential role of Gal-3 in AS. Methods: 226 patients (61.50% men) with severe AS undergoing surgical aortic valve (AV) replacement were recruited. In AVs, Gal-3 expression and its relationship with infammatory, osteogenic and angiogenic markers was assessed. Valve interstitial cells (VICs) were primary cultured to perform in vitro experiments. Results: Proteomic analysis revealed that intracellular Gal-3 was over-expressed in VICs of male AS patients. Gal-3 secretion was also higher in men’s VICs as compared to women’s. In human AVs, Gal-3 protein levels were signifcantly higher in men, with stronger immunostaining in VICs with myofbroblastic phenotype and valve endothelial cells. Gal-3 levels in AVs were positively correlated with infammatory markers in both sexes. Gal-3 expression was also posi tively correlated with osteogenic markers mainly in men AVs, and with angiogenic molecules only in this sex. In vitro, Gal-3 treatment induced expression of infammatory, osteogenic and angiogenic markers in male’s VICs, while it only upregulated infammatory and osteogenic molecules in women-derived cells. Gal-3 blockade with pharma cological inhibitors (modifed citrus pectin and G3P-01) prevented the upregulation of infammatory, osteogenic and angiogenic molecules. Conclusions: Gal-3 plays a sex-diferential role in the setting of AS, and it could be a new sex-specifc therapeutic target controlling pathological features of AS in VICs.
Open Access
Olfactory bulb proteomics reveals widespread proteostatic disturbances in mixed dementia and guides for potential serum biomarkers to discriminate alzheimer disease and mixed dementia phenotypes
(MDPI, 2021) Lachén Montes, Mercedes; Íñigo-Marco, Ignacio; Cartas Cejudo, Paz; Fernández Irigoyen, Joaquín; Santamaría Martínez, Enrique; Ciencias de la Salud; Osasun Zientziak; Gobierno de Navarra / Nafarroako Gobernua
The most common form of mixed dementia (MixD) is constituted by abnormal protein deposits associated with Alzheimer's disease (AD) that coexist with vascular disease. Although olfactory dysfunction is considered a clinical sign of AD-related dementias, little is known about the impact of this sensorial impairment in MixD at the molecular level. To address this gap in knowledge, we assessed olfactory bulb (OB) proteome-wide expression in MixD subjects (n = 6) respect to neurologically intact controls (n = 7). Around 9% of the quantified proteins were differentially expressed, pinpointing aberrant proteostasis involved in synaptic transmission, nucleoside monophosphate and carbohydrate metabolism, and neuron projection regeneration. In addition, network-driven proteomics revealed a modulation in cell-survival related pathways such as ERK, AKT, and the PDK1-PKC axis. Part of the differential OB protein set was not specific of MixD, also being deregulated across different tauopathies, synucleinopathies, and tardopathies. However, the comparative functional analysis of OB proteome data between MixD and pure AD pathologies deciphered commonalities and differences between both related phenotypes. Finally, olfactory pro-teomics allowed to propose serum Prolow-density lipoprotein receptor-related protein 1 (LRP1) as a candidate marker to differentiate AD from MixD phenotypes.