Browsing by Author "Perez-Acle, Tomas"

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    1-benzoyl-2-(2-nitrophenyl)-1H-benzimidazole derivatives: A novel approach to the development of new HIV-1 reverse transcriptase inhibitors
    (2007) Vásquez Velásquez, David; Lagos Arévalo, Carlos Fernando; Mella Raipán, Jaime Alberto; González Contreras, Luis Gerardo; Ebensperger González, Roberto Alejandro; Alvarez Figueroa, María Javiera; Sáez Moya, Edmundo Alfredo; Pessoa Mahana, Hernán; Araya Secchi, Raul; Gonzalez Wong, Angel; Perez-Acle, Tomas; Pessoa Mahana, Carlos David
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    An eleven amino acid residue deletion expands the substrate specificity of acetyl xylan esterase II (AXE II) from Penicillium purpurogenum
    (2008) Colombres, Marcela; Garate, Jose A.; Lagos, Carlos F.; Araya-Secchi, Raul; Norambuena, Patricia; Quiroz, Soledad; Larrondo, Luis; Perez-Acle, Tomas; Eyzaguirre, Jaime
    The soft-rot fungus Penicillium purpurogenum secretes to the culture medium a variety of enzymes related to xylan biodegradation, among them three acetyl xylan esterases (AXE I, II and III). AXE II has 207 amino acids; it belongs to family 5 of the carbohydrate esterases and its structure has been determined by X-ray crystallography at 0.9 angstrom resolution (PDB 1G66). The enzyme possesses the alpha/beta hydrolase fold and the catalytic triad typical of serine esterases (Ser90, His187 and Asp175). AXE II can hydrolyze esters of a large variety of alcohols, but it is restricted to short chain fatty acids. An analysis of its three-dimensional structure shows that a loop that covers the active site may be responsible for this strict specificity. Cutinase, an enzyme that hydrolyzes esters of long chain fatty acids and shows a structure similar to AXE II, lacks this loop. In order to generate an AXE II with this broader specificity, the preparation of a mutant lacking residues involving this loop (Gly104 to Ala114) was proposed. A set of molecular simulation experiments based on a comparative model of the mutant enzyme predicted a stable structure. Using site-directed mutagenesis, the loop's residues have been eliminated from the AXE II cDNA. The mutant protein has been expressed in Aspergillus nidulans A722 and Pichia pastoris, and it is active towards a range of fatty acid esters of up to at least 14 carbons. The availability of an esterase with broader specificity may have biotechnological applications for the synthesis of sugar esters.
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    Genome analysis and detection of a Chilean isolate of Grapevine leafroll associated virus-3
    (2008) Engel, Esteban A.; Girardi, Cristobal; Escobar, Paula F.; Arredondo, Vania; Dominguez, Calixto; Perez-Acle, Tomas; Valenzuela, Pablo D. T.
    The complete genome of the Chilean isolate Cl-766 of Grapevine leafroll-associated virus-3 (GLRaV-3) has been sequenced. This is the first genome sequence obtained from a GLRaV-3 isolate of the Southern hemisphere. The genomic RNA of 17,919 nucleotides contains 13 open reading frames (ORFs) with 5' and 3' untranslated regions (UTR) of 158 and 277 nucleotides, respectively. Comparison with NY1, the only isolate with complete genomic sequence available today, shows 97.6% nucleotide identity between the two isolates. Examination of the genome variability shows that most of the genetic diversity is concentrated in ORF1a. Three additional isolates from different geographic regions of Chile were partially sequenced as well, one which showed sequence divergence with respect to the other local and foreign isolates, indicative of different evolutionary constrains. Immunodetection systems were developed using monoclonal and polyclonal antibodies produced against the recombinant major coat protein of GLRaV-3, providing sensitive and specific detection using a triple antibody sandwich-enzyme linked immunosorbent assay (TAS-ELISA) and an immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) assay.
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    Identification of master regulator genes controlling pathogenic CD4+ T cell fate in inflammatory bowel disease through transcriptional network analysis
    (2024) Jimenez, Jose M.; Contreras-Riquelme, J. Sebastian; Vidal, Pia M.; Prado, Carolina; Bastias, Macarena; Meneses, Claudio; Martin, Alberto J. M.; Perez-Acle, Tomas; Pacheco, Rodrigo
    Inflammatory bowel diseases (IBD) are a group of chronic inflammatory conditions of the gastrointestinal tract associated with multiple pathogenic factors, including dysregulation of the immune response. Effector CD4(+) T cells and regulatory CD4(+) T cells (Treg) are central players in maintaining the balance between tolerance and inflammation. Interestingly, genetic modifications in these cells have been implicated in regulating the commitment of specific phenotypes and immune functions. However, the transcriptional program controlling the pathogenic behavior of T helper cells in IBD progression is still unknown. In this study, we aimed to find master transcription regulators controlling the pathogenic behavior of effector CD4(+) T cells upon gut inflammation. To achieve this goal, we used an animal model of IBD induced by the transfer of na & iuml;ve CD4(+) T cells into recombination-activating gene 1 (Rag1) deficient mice, which are devoid of lymphocytes. As a control, a group of Rag1 -/- mice received the transfer of the whole CD4(+) T cells population, which includes both effector T cells and Treg. When gut inflammation progressed, we isolated CD4(+) T cells from the colonic lamina propria and spleen tissue, and performed bulk RNA-seq. We identified differentially up- and down-regulated genes by comparing samples from both experimental groups. We found 532 differentially expressed genes (DEGs) in the colon and 30 DEGs in the spleen, mostly related to Th1 response, leukocyte migration, and response to cytokines in lamina propria T-cells. We integrated these data into Gene Regulatory Networks to identify Master Regulators, identifying four up-regulated master gene regulators (Lef1, Dnmt1, Mybl2, and Jup) and only one down-regulated master regulator (Foxo3). The altered expression of master regulators observed in the transcriptomic analysis was confirmed by qRT-PCR analysis and found an up-regulation of Lef1 and Mybl2, but without differences on Dnmt1, Jup, and Foxo3. These two master regulators have been involved in T cells function and cell cycle progression, respectively. We identified two master regulator genes associated with the pathogenic behavior of effector CD4(+) T cells in an animal model of IBD. These findings provide two new potential molecular targets for treating IBD.