Browsing by Author "Carvallo, Loreto"

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    Non-canonical Wnt Signaling Induces Ubiquitination and Degradation of Syndecan
    (AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2010) Carvallo, Loreto; Munoz, Rosana; Bustos, Francisco; Escobedo, Noelia; Carrasco, Hector; Olivares, Gonzalo; Larrain, Juan
    Dynamic regulation of cell adhesion receptors is required for proper cell migration in embryogenesis, tissue repair, and cancer. Integrins and Syndecan4 (SDC4) are the main cell adhesion receptors involved in focal adhesion formation and are required for cell migration. SDC4 interacts biochemically and functionally with components of the Wnt pathway such as Frizzled7 and Dishevelled. Non-canonical Wnt signaling, particularly components of the planar cell polarity branch, controls cell adhesion and migration in embryogenesis and metastasic events. Here, we evaluate the effect of this pathway on SDC4. We have found that Wnt5a reduces cell surface levels and promotes ubiquitination and degradation of SDC4 in cell lines and dorsal mesodermal cells from Xenopus gastrulae. Gain-and loss-of-function experiments demonstrate that Dsh plays a key role in regulating SDC4 steady-state levels. Moreover, a SDC4 deletion construct that interacts inefficiently with Dsh is resistant to Wnt5a-induced degradation. Non-canonical Wnt signaling promotes monoubiquitination of the variable region of SDC4 cytoplasmic domain. Mutation of these specific residues abrogates ubiquitination and results in increased SDC4 steady-state levels. This is the first example of a cell surface protein ubiquitinated and degraded in a Wnt/Dsh-dependent manner.
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    Syndecan-1 regulates BMP signaling and dorso-ventral patterning of the ectoderm during early Xenopus development
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009) Olivares, Gonzalo H.; Carrasco, Hector; Aroca, Francisco; Carvallo, Loreto; Segovia, Fabian; Larrain, Juan
    Extracellular regulation of growth factor signaling is a key event for embryonic patterning. Heparan sulfate proteoglycans (HSPG) are among the molecules that regulate this signaling during embryonic development. Here we study the function of syndecan1 (Syn1), a cell-surface HSPG expressed in the non-neural ectoderm during early development of Xenopus embryos. Overexpression of Xenopus Syn1 (xSyn1) mRNA is Sufficient to reduce BMP signaling, induce chordin expression and rescue dorso-ventral patterning in ventrailized embryos. Experiments using chordin morpholinos established that xSyn1 mRNA can inhibit BM P signaling in the absence of chordin. Knockdown of xSyn1 resulted in a reduction of BMP signaling and expansion of the neural plate with the concomitant reduction of the non-neural ectoderm. Overexpression of xSyn1 mRNA in xSyn1 morphant embryos resulted in a biphasic effect, with BMP being inhibited at high concentrations and activated at low concentrations of xSyn1. Interestingly, the function of xSyn1 on dorso-ventral patterning and BMP signaling is specific for this HSPG. In summary, we report that xSyn1 regulates dorso-ventral patterning of the ectoderm through modulation of BMP signaling. (C) 2009 Elsevier Inc. All rights reserved.
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    Transcriptional Control of Glutaredoxin GRXC9 Expression by a Salicylic Acid-Dependent and NPR1-Independent Pathway in Arabidopsis
    (2015) Herrera Vásquez, Ariel Esteban; Carvallo, Loreto; Blanco, Francisca; Tobar, Mariola; Villarroel Candia, Eva; Vicente Carbajosa, Jesús; Salinas, Paula; Holuigue Barros, María Loreto