Browsing by Author "Herrera Vásquez, Ariel Esteban"

Now showing 1 - 6 of 6
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    Chemical inhibition of the histone acetyltransferase activity in Arabidopsis thaliana
    (2017) Aquea Zeballos, José Felipe; Timmermann, Tania; Herrera Vásquez, Ariel Esteban
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    Salicylic acid and reactive oxygen species interplay in the transcriptional control of defense genes expression
    (2015) Herrera Vásquez, Ariel Esteban; Salinas Salvo, Paula Andrea Ximena; Holuigue Barros, María Loreto
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    TGA class II transcription factors are essential to restrict oxidative stress in response to UV-B stress in Arabidopsis
    (2021) Herrera Vásquez, Ariel Esteban; Fonseca Cárdenas, Alejandro Alfredo; Ugalde Valdivia, José Manuel; Lamig Giannini, Liliana Andrea; Seguel Avello, Aldo Luis; Moyano Yugovic, Tomás Custodio; Gutiérrez Ilabaca, Rodrigo Antonio; Salinas, Paula; Vidal, Elena A.; Holuigue Barros, Loreto
    Plants possess a robust metabolic network for sensing and controlling reactive oxygen species (ROS) levels upon stress conditions. Evidence shown here supports a role for TGA class II transcription factors as critical regulators of genes controlling ROS levels in the tolerance response to UV-B stress in Arabidopsis. First, tga256 mutant plants showed reduced capacity to scavenge H2O2 and restrict oxidative damage in response to UV-B, and also to methylviologen-induced photooxidative stress. The TGA2 transgene (tga256/TGA2 plants) complemented these phenotypes. Second, RNAseq followed by clustering and Gene Ontology term analyses indicate that TGA2/5/6 positively control the UV-B-induced expression of a group of genes with oxidoreductase, glutathione transferase, and glucosyltransferase activities, such as members of the glutathione S-transferase Tau subfamily (GSTU), which encodes peroxide-scavenging enzymes. Accordingly, increased glutathione peroxidase activity triggered by UV-B was impaired in tga256 mutants. Third, the function of TGA2/5/6 as transcriptional activators of GSTU genes in the UV-B response was confirmed for GSTU7, GSTU8, and GSTU25, using quantitative reverse transcription–PCR and ChIP analyses. Fourth, expression of the GSTU7 transgene complemented the UV-B-susceptible phenotype of tga256 mutant plants. Together, this evidence indicates that TGA2/5/6 factors are key regulators of the antioxidant/detoxifying response to an abiotic stress such as UV-B light overexposure.
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    Transcription factor TGA2 is essential for UV-B stress tolerance controlling oxidative stress in Arabidopsis
    (2020) Herrera Vásquez, Ariel Esteban; Fonseca Cárdenas, Alejandro Alfredo; Ugalde Valdivia, José Manuel; Lamig Giannini, Liliana Andrea; Seguel Avello, Aldo Luis; Moyano Yugovic, Tomás Custodio; Gutiérrez Ilabaca, Rodrigo Antonio; Salinas, Paula; Vidal, Elena A.; Holuigue Barros, Loreto
    Plants possess a diversity of Reactive Oxygen Species (ROS)-processing enzymes involved in sensing and controlling ROS levels under basal and stressful conditions. There is little information on the transcriptional regulators that control the expression of these ROS-processing enzymes, particularly at the onset of the defense response to abiotic stress. Filling this gap, this paper reports a critical role for Arabidopsis TGA class II factors (TGA2, TGA5, and TGA6) in the tolerance response to UV-B light and photooxidative stress, by activating the expression of genes with antioxidative roles. We identified two clusters of genes responsive to UV-B and activated by TGA2/5/6 were identified using RNAseq and clustering analysis. The GSTU gene family, which encodes glutathione transferase enzymes from the Tau subclass, was overrepresented in these clusters. We corroborated the TGA2-mediated activation in response to UV-B for three model genes (GSTU7, GSTU8, and GSTU25) using RT-qPCR and ChIP analyses. Interestingly, using tga256 mutant and TGA2- and GSTU7-complemented mutant plants, we demonstrated that TGA2-mediated induction of GSTU genes is essential to control ROS levels and oxidative damage after UV-B and MeV treatments. This evidence positions TGA class II factors, particularly TGA2, as a key players in the redox signaling network of Arabidopsis plants.
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    Transcriptional control of glutaredoxin GRXC9 by stress in Arabidopsis
    (2015) Herrera Vásquez, Ariel Esteban; Holuigue Barros, María Loreto; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas
    El Ácido Salicílico (SA) es una hormona que media la reprogramación transcripcional en el contexto de la respuesta de defensa a estrés en plantas. El gen GRXC9, que codifica para una glutarredoxina de Arabidopsis, es un gen inducido de forma temprana e independientemente del coactivador maestro NPR1. En esta tesis describimos el mecanismo de regulación transcripcional del gen modelo GRXC9 por SA. Inicialmente establecimos que la expresión de GRXC9 es inducida por exposición a luz UV-B a través en un mecanismo dependiente de SA e independiente de NPR1 validando su activación en una condición fisiológica. Análisis del promotor de GRXC9 indican que SA controla la transcripción del gen a través de dos elementos tipo-as-1 ubicados en la región proximal al inicio de la transcripción. Los factores de transcripción TGA2 y TGA3, están constitutivamente unidos a la región promotora de GRXC9. Concordantemente, el reclutamiento transitorio de la RNA polimerasa II al promotor de GRXC9 y la acumulación del transcrito detectados en plantas silvestres tratadas con SA, se pierde en plantas mutantes para los factores de transcripción TGA de la clase II (que incluyen a TGA2). A partir de esto, concluimos que la unión constitutiva de TGA2 es esencial para el control de la expresión de GRXC9. Finalmente, mediante el uso de plantas que sobre-expresan GRXC9 podemos concluir que GRXC9 regula negativamente su propia expresión formando parte del complejo unido a la región promotora que contiene los elementos tipo-as-1. Estos descubrimientos son integrados en un modelo que explica como SA controla la expresión de GRXC9 en el contexto de la respuesta de defensa a estrés.
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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