Browsing by Author "Martinez, J"

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    Galectin-8 binds specific beta 1 integrins and induces polarized spreading highlighted by asymmetric lamellipodia in Jurkat T cells
    (ELSEVIER INC, 2006) Carcamo, C; Pardo, E; Oyanadel, C; Bravo Zehnder, M; Bull, P; Caceres, M; Martinez, J; Massardo, L; Jacobelli, S; Gonzalez, A; Soza, A
    Integrin-mediated encounters of T cells with extracellular cues lead these cells to adhere to a variety of substrates and acquire a spread phenotype needed for their tissue incursions. We studied the effects of galectin-8 (Gal-8), beta-galactoside binding lectin, on Jurkat T cells. Immobilized Gal-8 bound alpha 1 beta 1 and alpha 5 beta 1 but not alpha 2 beta 1 and alpha 4 beta 1 and adhered these cells with similar kinetics to immobilized fibronectin (FN). Function-blocking experiments with monoclonal anti-integrin antibodies suggested that alpha 5 beta 1 is the main mediator of cell adhesion to this lectin. Gal-8, but not FN, induced extensive cell spreading frequently leading to a polarized phenotype characterized by an asymmetric lamellipodial protrusion. These morphological changes involved actin cytoskeletal rearrangements controlled by PI3K, Rac-1 and ERK1/2 activity. Gal-8-induced Rac-1 activation and binding to alpha 1 and alpha 5 integrins have not been described in any other cellular system. Strikingly, Gal-8 was also a strong stimulus on Jurkat cells in suspension, triggering ERK1/2 activation that in most adherent cells is instead dependent on cell attachment. In addition, we found that patients with systemic lupus erythematosus (SLE), a prototypic autoimmune disorder, produce Gal-8 autoantibodies that impede both its binding to integrins and cell adhesion. These are the first function-blocking autoantibodies reported for a member of the galectin family. These results indicate that Gal-8 constitutes a novel extracellular stimulus for T cells, able to bind specific beta 1 integrins and to trigger signaling pathways conducive to cell spreading. Gal-8 could modulate a wide range of T cell-driven immune processes that eventually become altered in autoimmune disorders. (C) 2005 Elsevier Inc. All rights reserved.
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    Successful liver transplantation and delivery in a woman with fulminant hepatic failure occurring during the second trimester of pregnancy
    (WILEY, 2006) Jarufe, N; Soza, A; Perez Ayuso, RM; Poblete, JA; Gonzalez, R; Guajardo, M; Hernandez, V; Riquelme, A; Arrese, M; Martinez, J
    Background: Severe liver dysfunction occurring during pregnancy is an unusual but dramatic event that poses special technical and ethical issues because it involves two lives. Methods an Results: We report the case of a 35-year-old woman with cryptogenic fulminant hepatic failure who underwent successful orthotopic liver transplantation at 22 weeks of pregnancy. After a relatively uneventful post-operative course she delivered a normal offspring at the 27th week of gestation. There were no obstetrical complications and neonatal outcome was excellent. After a year of follow-up, the patient is doing well,and the newborn has exhibited normal psychomotor and weight/height development. Conclusions: This case illustrates the challenge of treating fulminant hepatic failure during pregnancy and demonstrates that liver transplantation is a feasible therapeutic option for treatment of patients with this condition, allowing successful completion of pregnancy.