Browsing by Author "González de la Rosa, Alfonso"

Now showing 1 - 20 of 27
  • Thumbnail Image
    Item
    Antiribosomal-P autoantibodies from psychiatric lupus target a novel neuronal surface protein causing calcium influx and apoptosis
    (2007) Matus, Soledad; Torrealba, Fernando; Massardo Vega, Loreto; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Apical sorting of hepatitis B surface antigen (HBsAg) is independent of N-glycosylation and glycosylphosphatidylinositol-anchored protein segregation
    (1997) Marzolo Canales, María Paz; Bull Simpfendorfer, Paulina; González de la Rosa, Alfonso; Marzolo Canales, María Paz; Bull Simpfendorfer, Paulina; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Ciprofibrate, a Carcinogenic Peroxisome Proliferator, Increases the Phosphorylation of Epidermal-Growth Factor Receptor in Isolated Rat Hepatocytes
    (1993) Bronfman A., Miguel L.; Holuigue Barros, María Loreto; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Determinants of differential functions of galectin-8 on T cells and tumoral cells : interplay of galectin-8 isoforms, integrin and growth factor signaling pathways.
    (2014) Döger, Remziye; González de la Rosa, Alfonso; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
    Galectins are a subfamily of lectins involved in a variety of cellular processes mainly related with the immune system and cancer. Galectins are secreted through unconventional mechanisms, because they lack a signal peptide, and their carbohydrate recognition domains (CRD) bind to N-acetyllactosamine residues present on cell surface N- and O-glycoconjugates. Each of the 15 galectin family members can have redundant as well as particular functions depending on the structural organization of their CRDs, which is classified in three major groups: Monomeric chimera-type design (Gal-3); Homodimeric prototype (Gal-1, -2, -5, -7, -10, -11, -13, and -15); Tandem-repeat type with two different CRDs connected by a linker peptide (Gal-4, -6, -8, -9 and -12). The function of each particular member can also vary in different cellular contexts through mechanisms still not well understood, but likely dependent on differential subsets of glycoproteins and signaling pathways engaged. Therefore, understanding the role of a particular galectin requires to define the determinants of its variable functions in different cellular contexts.
  • Thumbnail Image
    Item
    Epidermal growth factor receptor endocytic traffic perturbation by phosphatidate phosphohydrolase inhibition : new strategy against cancer
    (2014) Shaughnessy, Ronan Patrick; Retamal, Claudio; Oyanadel, Claudia; Norambuena Pérez, Andrés; López, Alejandro; Bravo Zehnder, Marcela; Montecino, Fabián, J.; Metz Baer, Claudia Andrea; Soza Gajardo, Andrea; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Epidermal Growth Factor Receptor in Synaptic Fractions of the Rat Central Nervous System
    (1992) Faúndez González, Víctor; Garrido, Jorge; González de la Rosa, Alfonso; Holuigue Barros, María Loreto
  • Thumbnail Image
    Item
    Función de la proteína NSPA en la regulación de los receptores de NMDA en hipocampo.
    (2019) Espinoza Conlledo, Carmen Sofía; González de la Rosa, Alfonso; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
    El lupus eritematoso sistémico, prototipo de enfermedad autoinmune, frecuentemente manifiesta disfunciones cerebrales difusas que incluyen deficiencias cognitivas y psicosis en casos más extremos. Estas manifestaciones son parte del espectro de manifestaciones del lupus neuropsiquiátrico (LES-NP) cuyos mecanismos todavía no están bien dilucidados. Autoanticuerpos anti-proteína P ribosomal (Anti-P) se han asociado a psicosis lúpica y déficit cognitivo en pacientes con LES-NP. Nuestro laboratorio introdujo el concepto de que las manifestaciones cerebrales difusas del LES-NP involucrarían una reacción cruzada de los anticuerpos anti-P con una proteína de la superficie celular de función desconocida que llamamos NSPA (neuronal surface P antigen). En cerebro, la NSPA se expresa exclusivamente en neuronas y en regiones específicas tales como corteza e hipocampo. Para entender la patogenia de los anticuerpos anti-P en el LES-NP es necesario dilucidar la función de la NSPA en el cerebro. La estructura primaria de la NSPA muestra un dominio APC10 que sólo se ha descrito en E3 ubiquitin ligasas, sugiriendo que la NSPA podría ser una E3 ubiquitin ligasa. En base al fenotipo de un ratón que expresa una versión truncada de la NSPA que carece del dominio APC10 postulamos la siguiente hipótesis: La NSPA es una ubiquitin ligasa que regula los niveles del receptor de NMDA en la región post-sináptica. Para esto caracterizamos un ratón carente de NSPA evaluando si la NSPA es necesaria para la función del hipocampo y la transmisión sináptica, particularmente en procesos dependientes del receptor de NMDA, también evaluamos si la NSPA posee características de algún tipo de E3 ubiquitin ligasa. Encontramos que la NSPA se requiere para la transmisión glutamatérgica y la plasticidad sináptica mediada por los NMDARs, lo que se traduce en alteraciones en procesos de memoria espacial y de reconocimiento. La falta de NSPA lleva a una disminución de las subunidades GluN2 del NMDAR en la densidad post-sináptica. También se asocia a una reducción en la fosforilación de la subunidad GluN2B en la tirosina 1472, residuo que modula la endocitosis del NMDAR. Encontramos que la tirosina fosfatasa PTPN4 se ubiquitina y sus niveles de ubiquitinación se encuentran disminuidos en ratones que carecen de NSPA. Esto lleva a un aumento de la masa de PTPN4 en la región sináptica, resultando en una menor fosforilación del residuo de tirosina 1472 de la subunidad GluN2B del NMDAR involucrado en endocitosis. Además, la NSPA se requiere para la neurogénesis adulta en el giro dentado del hipocampo, proceso que también se ha asociado a función de los NMDARs. Por otra parte, vimos que la NSPA posee algunas características E3 ligasas del tipo RBR. Por lo tanto, nuestros resultados indican que la NSPA podría ser o formar parte de una E3 ubiquitin ligasa, que tiene como sustrato a la PTPN4, que a su vez regula los niveles de NMDAR en la región postsináptica y en consecuencia regula las funciones del hipocampo que dependen de estos receptores, incluyendo la memoria.
  • Thumbnail Image
    Item
    Galectin-8 binds specific β1 integrins and induces polarized spreading highlighted by asymmetric lamellipodia in Jurkat T cells
    (2006) Cárcamo, Claudio; Bull Simpfendorfer, Paulina; Massardo Vega, Loreto; González de la Rosa, Alfonso; Soza Gajardo, Andrea
  • Thumbnail Image
    Item
    Galectin-8 binds to LFA-1, blocks its interaction with ICAM-1 and is counteracted by anti-Gal-8 autoantibodies isolated from lupus patients
    (2013) Vicuña, Lucas; Pardo, Evelyn; Curkovic, Cristóbal; Doger, Remziye; Oyanadel, Claudia; Metz Baer, Claudia Andrea; Massardo Vega, Loreto; González de la Rosa, Alfonso; Soza Gajardo, Andrea
  • No Thumbnail Available
    Item
    Galectin-8 mediates fibrogenesis induced by cyclosporine in human gingival fibroblasts
    (2020) Patricio C. Smith; Metz Baer, Claudia Andrea; Peña, Adely de la; Oyanadel, Claudia; Ávila, Patricio; Arancibia, Rodrigo; Vicuña, Lucas; Retamal Villarroel, Claudio Enrique; Barake Sabbagh, M. Francisca; González de la Rosa, Alfonso; Soza Gajardo, Andrea
  • Thumbnail Image
    Item
    Galectin-8 promotes migration and proliferation and prevents apoptosis in U87 glioblastoma cells
    (2016) Metz Baer, Claudia Andrea; Döger, Remziye.; Riquelme Barrientos, Elizabeth Carolina.; Cortés Martínez, Priscilla Rocío; Holmes Videla, Christopher Edward; Shaughnessy, Ronan.; Oyanadel, Claudia.; Grabowski Pinto, Catalina.; González de la Rosa, Alfonso; Soza Gajardo, Andrea
    Abstract Background Glioblastoma is one of the most aggressive cancers of the brain. Malignant traits of glioblastoma cells include elevated migration, proliferation and survival capabilities. Galectins are unconventionally secreted glycan-binding proteins that modulate processes of cell adhesion, migration, proliferation and apoptosis by interacting with beta-galactosides of cell surface glycoproteins and the extracellular matrix. Galectin-8 is one of the galectins highly expressed in glioblastoma cells. It has a unique selectivity for terminally sialylated glycans recently found enhanced in these highly malignant cells. A previous study in glioblastoma cell lines reported that Gal-8 coating a plastic surface stimulates two-dimensional motility. Because in other cells Gal-8 arrests proliferation and induces apoptosis, here we extend its study by analyzing all of these processes in a U87 glioblastoma cell model. Methods We used immunoblot and RT-PCR for Gal-8 expression analysis, recombinant Gal-8 produced in a bacteria system for Gal-8 treatment of the cells, and shRNA in lentivirus transduction for Gal-8 silencing. Cell migration as assessed in transwell filters. Cell proliferation, cell cycle and apoptosis were analyzed by FACS. Results Gal-8 as a soluble stimulus triggered chemotactic migration of U87 cells across the polycarbonate filter of transwell chambers, almost as intensively as fetal bovine serum. Unexpectedly, Gal-8 also enhanced U87 cell growth. Co-incubation of Gal-8 with lactose, which blocks galectin–glycan interactions, abrogated both effects. Immunoblot showed Gal-8 in conditioned media reflecting its secretion. U87 cells transduced with silencing shRNA in a lentiviral vector expressed and secreted 30–40 % of their normal Gal-8 levels. These cells maintained their migratory capabilities, but decreased their proliferation rate and underwent higher levels of apoptosis, as revealed by flow cytometry analysis of cell cycle, CFSE and activated caspase-3 staining. Proliferation seemed to be more sensitive than migration to Gal-8 expression levels. Conclusions Gal-8, either secreted or exogenously enriched in the media, and acting through extracellular glycan interactions, constitutes a strong stimulus of directional migration in glioblastoma U87 cells and for the first time emerges as a factor that promotes proliferation and prevents apoptosis in cancerous cells. These properties could potentially contribute to the exaggerated malignancy of glioblastoma cells.Abstract Background Glioblastoma is one of the most aggressive cancers of the brain. Malignant traits of glioblastoma cells include elevated migration, proliferation and survival capabilities. Galectins are unconventionally secreted glycan-binding proteins that modulate processes of cell adhesion, migration, proliferation and apoptosis by interacting with beta-galactosides of cell surface glycoproteins and the extracellular matrix. Galectin-8 is one of the galectins highly expressed in glioblastoma cells. It has a unique selectivity for terminally sialylated glycans recently found enhanced in these highly malignant cells. A previous study in glioblastoma cell lines reported that Gal-8 coating a plastic surface stimulates two-dimensional motility. Because in other cells Gal-8 arrests proliferation and induces apoptosis, here we extend its study by analyzing all of these processes in a U87 glioblastoma cell model. Methods We used immunoblot and RT-PCR for Gal-8 expression analysis, recombinant Gal-8 produced in a bacteria system for Gal-8 treatment of the cells, and shRNA in lentivirus transduction for Gal-8 silencing. Cell migration as assessed in transwell filters. Cell proliferation, cell cycle and apoptosis were analyzed by FACS. Results Gal-8 as a soluble stimulus triggered chemotactic migration of U87 cells across the polycarbonate filter of transwell chambers, almost as intensively as fetal bovine serum. Unexpectedly, Gal-8 also enhanced U87 cell growth. Co-incubation of Gal-8 with lactose, which blocks galectin–glycan interactions, abrogated both effects. Immunoblot showed Gal-8 in conditioned media reflecting its secretion. U87 cells transduced with silencing shRNA in a lentiviral vector expressed and secreted 30–40 % of their normal Gal-8 levels. These cells maintained their migratory capabilities, but decreased their proliferation rate and underwent higher levels of apoptosis, as revealed by flow cytometry analysis of cell cycle, CFSE and activated caspase-3 staining. Proliferation seemed to be more sensitive than migration to Gal-8 expression levels. Conclusions Gal-8, either secreted or exogenously enriched in the media, and acting through extracellular glycan interactions, constitutes a strong stimulus of directional migration in glioblastoma U87 cells and for the first time emerges as a factor that promotes proliferation and prevents apoptosis in cancerous cells. These properties could potentially contribute to the exaggerated malignancy of glioblastoma cells.
  • Thumbnail Image
    Item
    IL-21 signaling pathway modulation in B lymphocytes by vitamin D in systemic lupus erythematosus
    (2019) Hirigoyen Pérez, Daniela María; González de la Rosa, Alfonso; Pontificia Universidad Católica de Chile. Escuela de Medicina
    El Lupus Eritematoso Sistémico (LES) es una enfermedad autoinmune, caracterizada por la activación de linfocitos B y la generación de autoanticuerpos, con una variedad de manifestaciones clínicas. Se ha reportado que los pacientes con LES tienen niveles más bajos de vitamina D que la población sana, lo que podría estar dado, en parte, a que estos pacientes deben evitar la exposición solar. La deficiencia de vitamina D puede jugar un rol en SLE, ya que recientemente, se ha descrito que esta vitamina puede modificar la respuesta inmune, reduciendo la proliferación y activación de linfocitos B, disminuyendo la producción de anticuerpos. Los mecanismos implicados en la acción de la vitamina D no están completamente dilucidados, pero si se demuestra que es efectiva como tratamiento, sería una droga segura y de bajo costo. La vitamina D podría disminuir la expresión de la interleuquina-21 (IL-21), citoquina tipo I que participa en la activación y diferenciación de linfocitos B, y alteraciones en su vía de señalización podrían inducir la generación de linfocitos B auto reactivos y producción de autoanticuerpos. Nuestra hipótesis fue que la vitamina D reduce la función de IL-21, definida como la expresión, la señalización y los niveles de IL-21, en una cohorte de mestiza de LES. El objetivo principal fue determinar si la suplementación con vitamina D tiene un efecto en los niveles de IL-21 y su vía de señalización en Linfocitos B de pacientes con LES. Para el primer objetivo, reclutamos pacientes con LES con hipovitaminosis que participaron en un protocolo de suplementación aleatorizado, doble ciego, controlado por placebo. No encontramos diferencias en las variables clínicas ni en la expresión del receptor de IL-21 (IL-21R) en linfocitos B en pacientes que recibieron vitamina D o placebo. Detectamos la IL-21 en linfocitos T activados, encontrando que la población de linfocitos T IL-21+ es mayor en pacientes con Lupus que en controles sanos. Para los otros objetivos, evaluamos el efecto de la vitamina D en la función de IL-21 en linfocitos T y B de controles sanos in vitro. La exposición a vitamina D no modificó la población de linfocitos T IL-21+ in vitro, también analizamos la expresión de IL-21R y la fosforilación de STAT3 (pSTAT3) en linfocitos B activados in vitro, expuestos a vitamina D, y observamos que la vitamina D no reduce la expresión de IL-21R o la fosforilación de STAT3 inducida por IL-21. Finalmente, caracterizamos dos polimorfismos de IL-21, rs907715 y rs6822844 en pacientes con Lupus, y observamos que están asociados con la fotosensibilidad y edad, y uso de metotrexato en pacientes con Lupus, respectivamente. Pese a que la vitamina D no influencia la señalización de IL-21 en linfocitos B, esta es la primera vez que la expresión de IL-21R y pSTAT3 se estudian en linfocitos B expuestos a vitamina D. Estos hallazgos son relevantes para ayudar a dilucidar los mecanismos de inmunomodulación de la vitamina D.
  • Thumbnail Image
    Item
    Increased Expression of C-Rel, From the Nf-Kb/Rel Family, in T Cells From Patients With Systemic Lupus Erythematosus
    (2000) Burgos, P.; Bull Simpfendorfer, Paulina; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    N-Glycosylation instead of cholesterol mediates oligomerization and apical sorting of GPI-APs in FRT cells
    (2011) Imjeti, N.; Fuente Ortega, Erwin de la.; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Neuronal surface P antigen (NSPA) modulates postsynaptic NMDAR stability through ubiquitination of tyrosine phosphatase PTPMEG
    (2020) Espinoza, Sofía; Barake Sabbagh, M. Francisca; Carvajal Cachaña, Francisco Javier; Segovia Miranda, Fabián Josué; Cerpa Nebott, Waldo Francisco; González de la Rosa, Alfonso; Arredondo, Sebastián B.; Guerrero, Fernanda G.; Valenzuela, David M.; Wyneken, Ursula
    Abstract Background 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.
  • Thumbnail Image
    Item
    Nucleotide P2Y(1) receptor regulates EGF receptor mitogenic signaling and expression in epithelial cells
    (2007) Buvinic, Sonja.; Huidobro-Toro, Juan Pablo.; González de la Rosa, Alfonso
  • Thumbnail Image
    Item
    Polarized Traffic of LRP1 Involves AP1B and SNX17 Operating on Y- dependent Sorting Motifs in Different Pathways
    (2009) Donoso, M.; Cancino Henríquez, Jorge Antonio.; Retamal Villarroel, Claudio Enrique.; González de la Rosa, Alfonso; Marzolo Canales, María Paz
  • Thumbnail Image
    Item
    Predictors of damage accrual in systemic lupus erythematosus : a longitudinal observational study with focus on neuropsychological factors and anti-neuronal antibodies
    (2019) Mimica, M.; Barra, I.; Ormeño, R.; Flores, P.; Calderón Pinto, Jorge; Padilla Pérez, Oslando; Bravo Zehnder, Marcela; González de la Rosa, Alfonso; Massardo Vega, Loreto
  • Thumbnail Image
    Item
    Propranolol Restricts the Mobility of Single EGF-Receptors on the Cell Surface before Their Internalization
    (2013) Otero, C.; Linke, M.; Sánchez, P.; González de la Rosa, Alfonso; Schaap, I.
  • Thumbnail Image
    Item
    Role of Copper in Prion Diseases: Deleterious or Beneficial?
    (2006) Varela-Nallar, L.; González de la Rosa, Alfonso; Inestrosa Cantín, Nibaldo