Browsing by Author "Pino, Karla"

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    A cis-Acting Element Present within the gag Open Reading Frame Negatively Impacts on the Activity of the HIV-1 IRES
    (2013) Valiente Echeverria, Fernando; Vallejos, Maricarmen; Monette, Anne; Pino, Karla; Letelier, Alejandro; Huidobro Toro, J. Pablo; Mouland, Andrew J.; López Lastra, Marcelo Andrés
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    Andes Virus Antigens Are Shed in Urine of Patients with Acute Hantavirus Cardiopulmonary Syndrome
    (AMER SOC MICROBIOLOGY, 2009) Godoy, Paula; Marsac, Delphine; Stefas, Elias; Ferrer, Pablo; Tischler, Nicole D.; Pino, Karla; Ramdohr, Pablo; Vial, Pablo; Valenzuela, Pablo D. T.; Ferres, Marcela; Veas, Francisco; Lopez Lastra, Marcelo
    Hantavirus cardiopulmonary syndrome (HCPS) is a highly pathogenic emerging disease (40% case fatality rate) caused by New World hantaviruses. Hantavirus infections are transmitted to humans mainly by inhalation of virus-contaminated aerosol particles of rodent excreta and secretions. At present, there are no antiviral drugs or immunotherapeutic agents available for the treatment of hantaviral infection, and the survival rates for infected patients hinge largely on early virus recognition and hospital admission and aggressive pulmonary and hemodynamic support. In this study, we show that Andes virus (ANDV) interacts with human apolipoprotein H (ApoH) and that ApoH-coated magnetic beads or ApoH-coated enzyme-linked immunosorbent assay plates can be used to capture and concentrate the virus from complex biological mixtures, such as serum and urine, allowing it to be detected by both immunological and molecular approaches. In addition, we report that ANDV-antigens and infectious virus are shed in urine of HCPS patients.
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    Association of single-nucleotide polymorphisms in IL28B, but not TNF-alpha, with severity of disease caused by andes virus
    (2015) Angulo, Jenniffer; Pino, Karla; Echeverria-Chagas, Natalia; Marco, Claudia; Martinez-Valdebenito, Constanza; Galeno, Héctor; Villagra, Eliecer; Vera, Lilian; Lagos, Natalia; Miquel P., Juan Francisco
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    Detection of high biliary and fecal viral loads in patients with chronic hepatitis C virus infection
    (2017) Monrroy Bravo, Hugo Alfonso; Angulo, J.; Pino, Karla; Labbé, P.; Miquel P., Juan Francisco; López Lastra, Marcelo Andrés; Soza, Alejandro
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    Effect of ezetimibe in HCV viral load after liver transplantation
    (2016) Monrroy Bravo, Hugo Alfonso; Angulo, J.; Pino, Karla; Labbé, P.; López Lastra, Marcelo Andrés; Soza, Alejandro
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    Functional and Structural Analysis of the Internal Ribosome Entry Site Present in the mRNA of Natural Variants of the HIV-1
    (PUBLIC LIBRARY SCIENCE, 2012) Vallejos, Maricarmen; Carvajal, Felipe; Pino, Karla; Navarrete, Camilo; Ferres, Marcela; Pablo Huidobro Toro, Juan; Sargueil, Bruno; Lopez Lastra, Marcelo
    The 5'untranslated regions (UTR) of the full length mRNA of the HIV-1 proviral clones pNL4.3 and pLAI, harbor an internal ribosomal entry site (IRES). In this study we extend this finding by demonstrating that the mRNA 5'UTRs of natural variants of HIV-1 also exhibit IRES-activity. Cap-independent translational activity was demonstrated using bicistronic mRNAs in HeLa cells and in Xenopus laevis oocytes. The possibility that expression of the downstream cistron in these constructs was due to alternative splicing or to cryptic promoter activity was ruled out. The HIV-1 variants exhibited significant 5'UTR nucleotide diversity with respect to the control sequence recovered from pNL4.3. Interestingly, translational activity from the 5'UTR of some of the HIV-1 variants was enhanced relative to that observed for the 5'UTR of pNL4.3. In an attempt to explain these findings we probed the secondary structure of the variant HIV-1 5'UTRs using enzymatic and chemical approaches. Yet subsequent structural analyses did not reveal significant variations when compared to the pNL4.3-5'UTR. Thus, the increased IRES-activity observed for some of the HIV-1 variants cannot be ascribed to a specific structural modification. A model to explain these findings is proposed.
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    Genetic variations in host IL28B links to the detection of peripheral blood mononuclear cells-associated hepatitis C virus RNA in chronically infected patients
    (2013) Angulo, Jenniffer; Pino, Karla; Pavez, C.; Biel, F.; Labbé, Pilar; Miquel P., Juan Francisco; Soza, Alejandro; López Lastra, Marcelo Andrés
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    Infection of human monocyte-derived dendritic cells by ANDES Hantavirus enhances pro-inflammatory state, the secretion of active MMP-9 and indirectly enhances endothelial permeability
    (2011) Marsac, Delphine; García, Stephanie; Pino, Karla; Ferrés Garrido, Marcela Viviana; López Lastra, Marcelo Andrés; Kalergis Parra, Alexis Mikes; Fournet, Alexandra; Aguirre, Adam; Veas, Francisco
    Abstract Background Andes virus (ANDV), a rodent-borne Hantavirus, is the major etiological agent of Hantavirus cardiopulmonary syndrome (HCPS) in South America, which is mainly characterized by a vascular leakage with high rate of fatal outcomes for infected patients. Currently, neither specific therapy nor vaccines are available against this pathogen. ANDV infects both dendritic and epithelial cells, but in despite that the severity of the disease directly correlates with the viral RNA load, considerable evidence suggests that immune mechanisms rather than direct viral cytopathology are responsible for plasma leakage in HCPS. Here, we assessed the possible effect of soluble factors, induced in viral-activated DCs, on endothelial permeability. Activated immune cells, including DC, secrete gelatinolytic matrix metalloproteases (gMMP-2 and -9) that modulate the vascular permeability for their trafficking. Methods A clinical ANDES isolate was used to infect DC derived from primary PBMC. Maturation and pro-inflammatory phenotypes of ANDES-infected DC were assessed by studying the expression of receptors, cytokines and active gMMP-9, as well as some of their functional status. The ANDES-infected DC supernatants were assessed for their capacity to enhance a monolayer endothelial permeability using primary human vascular endothelial cells (HUVEC). Results Here, we show that in vitro primary DCs infected by a clinical isolate of ANDV shed virus RNA and proteins, suggesting a competent viral replication in these cells. Moreover, this infection induces an enhanced expression of soluble pro-inflammatory factors, including TNF-α and the active gMMP-9, as well as a decreased expression of anti-inflammatory cytokines, such as IL-10 and TGF-β. These viral activated cells are less sensitive to apoptosis. Moreover, supernatants from ANDV-infected DCs were able to indirectly enhance the permeability of a monolayer of primary HUVEC. Conclusions Primary human DCs, that are primarily targeted by hantaviruses can productively be infected by ANDV and subsequently induce direct effects favoring a proinflammatory phenotype of infected DCs. Finally, based on our observations, we hypothesize that soluble factors secreted in ANDV-infected DC supernatants, importantly contribute to the endothelial permeability enhancement that characterize the HCPS.
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    LDL particle size and antioxidant HDL function improve after sustained virological response in patients with chronic HCV
    (2022) Ignacio Vargas, Jose; Rivera, Katherine; Arrese, Marco; Benitez, Carlos; Barrera, Francisco; Hugo, Monrroy; Pablo Arab, Juan; Pino, Karla; Barrera, Aldo; Lopez-Lastra, Marcelo; Rigotti, Attilio; Soza, Alejandro
    HCV infection is associated with an increased incidence of cardiovascular (CV) events. Mechanisms underlying this association remain unknown. In our study, twenty HCV patients (median age 60.5 years, 65% male and 80% with cirrhosis) were evaluated prior, during and after direct-acting antiviral treatment. Ninety percent of patients achieved sustained virological response (SVR). Significant changes were observed in LDL particle size index, measured by LDL-C/apoB ratio, which increased after treatment (p = 0.023). In addition, HDL antioxidant capacity improved gradually from 34.4% at baseline to 42.4% at 4 weeks (p = 0.011), 65.9% at end of treatment EOT (p = 0.002) and remained elevated at 12-week (p = 0.001) after EOT compared to baseline values. Our findings suggest that a shift to a less atherogenic lipid profile may be a possible mechanism associated with CV risk reduction in patients with HCV infection achieving SVR. (c) 2021 Fundacion Clinica Medica Sur, A.C. Published by Elsevier Espana, S.L.U. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
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    Non-canonical translation initiation of the spliced mRNA encoding the human T-cell leukemia virus type 1 basic leucine zipper protein
    (2018) Cáceres, C. Joaquín; Angulo, Jenniffer; Lowy de la Torre, Fernando; Contreras, Nataly; Walters, Beth; Olivares, Eduardo; Allouche, Delphine; Merviel, Anne; Pino, Karla; Sargueil, Bruno; Thompson, Sunnie R.; López Lastra, Marcelo Andrés
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    Polypyrimidine tract-binding protein binds to the 5' untranslated region of the mouse mammary tumor virus mRNA. and stimulates cap-independent translation initiation
    (2016) Cáceres, Carlos J.; Contreras, Nataly; Angulo, Jenniffer; Vera Otarola, Jorge; Pino Ajenjo, Constanza; Llorian, Miriam; Ameur, Melissa; Lisboa, Francisco; Pino, Karla; López Lastra, Marcelo Andrés; Lowy de la Torre, Fernando; Sargueil, Bruno
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    Post-translational modifications of hnRNP A1 differentially modulate retroviral IRES-mediated translation initiation
    (2020) Barrera, Aldo; Ramos, Hade; Vera-Otarola, Jorge; Fernandez-Garcia, Leandro; Angulo, Jenniffer; Olguin, Valeria; Pino, Karla; Mouland, Andrew J.; Lopez-Lastra, Marcelo
    The full-length mRNAs of the human immunodeficiency virus type-1 (HIV-1), the human T-cell lymphotropic virus type-1 (HTLV-1), and the mouse mammary tumor virus (MMTV) harbor IRESs. The activity of the retroviral-IRESs requires IRES-transacting factors (ITAFs), being hnRNP A1, a known ITAF for the HIV-1 IRES. In this study, we show that hnRNP A1 is also an ITAF for the HTLV-1 and MMTV IRESs. The MMTV IRES proved to be more responsive to hnRNP A1 than either the HTLV-1 or the HIV-1 IRESs. The impact of post-translational modifications of hnRNP A1 on HIV-1, HTLV-1 and MMTV IRES activity was also assessed. Results show that the HIV-1 and HTLV-1 IRESs were equally responsive to hnRNP A1 and its phosphorylation mutants S4A/S6A, S4D/S6D and S199A/D. However, the S4D/S6D mutant stimulated the activity from the MMTV-IRES to levels significantly higher than the wild type hnRNP A1. PRMT5-induced symmetrical di-methylation of arginine residues of hnRNP A1 enabled the ITAF to stimulate the HIV-1 and HTLV-1 IRESs while reducing the stimulatory ability of the ITAF over the MMTV IRES. We conclude that retroviral IRES activity is not only dependent on the recruited ITAFs but also relies on how these proteins are modified at the post-translational level.
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    Structural domains within the HIV-1 mRNA. and the ribosomal protein S25 influence cap-independent translation initiation
    (2016) Carvajal, Felipe; Vallejos, Maricarmen; Walters, Beth; Contreras, Nataly; Hertz, Marla I.; Olivares, Eduardo; Cáceres, Carlos J.; Pino, Karla; Letelier, Alejandro; López Lastra, Marcelo Andrés; Thompson, Sunnie R.
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    Targeting deoxyhypusine hydroxylase activity impairs cap-independent translation initiation driven by the 5'untranslated region of the HIV-1, HTLV-1, and MMTV mRNAs
    (2016) Cáceres, C. Joaquín; Angulo, Jenniffer; Contreras, Nataly; Pino, Karla; Vera Otarola, Jorge; López Lastra, Marcelo Andrés
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    The Andes Hantavirus NSs Protein Is Expressed from the Viral Small mRNA by a Leaky Scanning Mechanism
    (AMER SOC MICROBIOLOGY, 2012) Vera Otarola, Jorge; Solis, Loretto; Soto Rifo, Ricardo; Ricci, Emiliano P.; Pino, Karla; Tischler, Nicole D.; Ohlmann, Theophile; Darlix, Jean Luc; Lopez Lastra, Marcelo
    The small mRNA (SmRNA) of all Bunyaviridae encodes the nucleocapsid (N) protein. In 4 out of 5 genera in the Bunyaviridae, the smRNA encodes an additional nonstructural protein denominated NSs. In this study, we show that Andes hantavirus (ANDV) SmRNA encodes an NSs protein. Data show that the NSs protein is expressed in the context of an ANDV infection. Additionally, our results suggest that translation initiation from the NSs initiation codon is mediated by ribosomal subunits that have bypassed the upstream N protein initiation codon through a leaky scanning mechanism.
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    The double-stranded RNA-binding protein, Staufen1 is an IRES-transacting factor regulating HIV-1 cap-independent translation initiation
    (2022) Ramos, Hade; Monette, Anne; Niu, Meijuan; Barrera, Aldo; Lopez-Ulloa, Brenda; Fuentes, Yazmin; Guizar, Paola; Pino, Karla; DesGroseillers, Luc; Mouland, Andrew J.; Lopez-Lastra, Marcelo
    Translation initiation of the viral genomic mRNA (vRNA) of human immunodeficiency virus-type 1 (HIV-1) can be mediated by a cap- or an internal ribosome entry site (IRES)-dependent mechanism. A previous report shows that Staufen1, a cellular double-stranded (ds) RNA-binding protein (RBP), binds to the 5'untranslated region (5'UTR) of the HIV-1 vRNA and promotes its cap-dependent translation. In this study, we now evaluate the role of Staufen1 as an HIV-1 IRES-transacting factor (ITAF). We first confirm that Staufen1 associates with both the HIV-1 vRNA and the Gag protein during HIV-1 replication. We found that in HIV-1-expressing cells, siRNA-mediated depletion of Staufen1 reduces HIV-1 vRNA translation. Using dual-luciferase bicistronic mRNAs, we show that the siRNA-mediated depletion and cDNA-mediated overexpression of Staufen1 acutely regulates HIV-1 IRES activity. Furthermore, we show that Staufenl-vRNA interaction is required for the enhancement of HIV-1 IRES activity. Interestingly, we find that only Staufen1 harboring an intact dsRNA-binding domain 3 (dsRBD3) rescues HIV-1 IRES activity in Staufen1 CRISPR-Cas9 gene edited cells. Finally, we show that the expression of Staufen1-dsRBD3 alone enhances HIV-1 IRES activity. This study provides evidence of a novel role for Staufen1 as an ITAF promoting HIV-1 vRNA IRES activity.
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    The Elav-like protein HuR exerts translational control of viral internal ribosome entry sites
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009) Rivas Aravena, Andrea; Ramdohr, Pablo; Vallejos, Maricarmen; Valiente Echeverria, Fernando; Dormoy Raclet, Virginie; Rodriguez, Felipe; Pino, Karla; Holzmann, Cristian; Huidobro Toro, J. Pablo; Gallouzi, Imed Eddine; Lopez Lastra, Marcelo
    The human embryonic-lethal abnormal vision (ELAV)-like protein. HuR, has been recently found to be involved in the regulation of protein synthesis. In this study we show that HuR participates in the translational control of the HIV-1 and HCV IRES elements. HuR functions as a repressor of HIV-1]RES activity and acts as an activator of the HCV]RES. The effect of HuR was evaluated in three independent experimental systems, rabbit reticulocyte lysate, HeLa cells, and Xenopus laevis oocytes, using both overexpression and knockdown approaches. Furthermore, results suggest that HuR mediated regulation of HIV-1 and HCV IRESes does not require direct binding of the protein to the RNA nor does it need the nuclear translocation of the IRES-containing RNAs. Finally, we show that HuR has a negative impact on post-integration steps of the HIV-1 replication cycle. Thus, our observations yield novel insights into the role of HuR in the post-transcriptional regulation of HCV and HIV-1 gene expression. (C) 2009 Elsevier Inc. All rights reserved.
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    The Internal Ribosome Entry Site of Dengue Virus mRNA Is Active When Cap-Dependent Translation Initiation Is Inhibited
    (2021) Fernandez-Garcia, Leandro; Angulo, Jenniffer; Ramos, Hade; Barrera, Aldo; Pino, Karla; Vera-Otarola, Jorge; Lopez-Lastra, Marcelo
    Dengue virus (DENV) is an enveloped, positive-sense, single-stranded RNA virus belonging to the Flaviviridae family. Translation initiation of DENV mRNA can occur by a cap-dependent or a cap-independent mechanism. Two non-mutually exclusive cap-independent mechanisms of translation initiation have been described for DENV mRNA. The first corresponds to a 5'-end-dependent, internal ribosome entry site (IRES)-independent mechanism, while the second relies on IRES-dependent initiation. In this report, we study the recently discovered DENV IRES. The results show that the DENV IRES is functional in the rabbit reticulocyte lysate (RRL). In accordance, the activity of the DENV IRES was resistant to the cleavage of eukaryotic initiation factor 4G (eIF4G) by the Foot-and-mouth disease virus leader protease in RRL In cells, the DENV IRES exhibited only marginal activity under standard culture conditions. The DENV IRES showed weak activity in HEK 293T cells; however, DEW IRES activity was significantly enhanced in HEK 293T cells expressing Human rhinovirus 2A protease. These findings suggest that the DENV IRES enables viral protein synthesis under conditions that suppress canonical translation initiation.
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    Urinary leukotriene and Bcl I polymorphism of glucocorticoid receptor gene in preschoolers with recurrent wheezing and high risk of asthma
    (2016) Morales, M.; Flores, C.; Pino, Karla; Angulo, J.; López Lastra, Marcelo Andrés; Castro Rodríguez, José Antonio