http://repositoriodigital.ipn.mx/handle/123456789/2181 2026-03-09T15:43:46Z http://repositoriodigital.ipn.mx/handle/123456789/9171 Title: Transcriptional Activation by an URE4-like Sequence in the EhPgp1 Gene Core Promoter Authors: Ramírez, ME; Pérez, DG; Náder E, E; Gómez, C Abstract: EhPgp1 is one of the multidrug resistance genes expressed in drug resistant trophozoites from Entamoeba histolytica. Previous studies in our laboratory have demonstrated that two C/EBP sites participate in the transcriptional activation of this gene. However there is other relevant region that also governs the regulation of EhPgp1 expression in clone C2. In this report we provide evidence that transcription of the EhPgp1 gene is at least partly regulated by the cis-acting R9 repeated sequences and EhEBP1 protein. Structural analysis of the region from -234 to -197 bp shows the presence of two repeated sequences of 9 bp [R9(1) and R9(2)] located at -226 to -203 bp. Deletions and mutations analysis of the R9 motifs significantly reduced promoter activity in trophozoites from clone C2. EMSA experiments revealed specific binding of nuclear proteins from E. histolytica to the R9 sequence. While competition assays showed that the presence of more than one R9 sequence is necessary for a strong DNA-protein interaction. Moreover, Western blot experiments with partially-purified proteins interacting with the R9 motif and antibodies against EhEBP1, recognized a 28 kDa protein. Interestingly, this antibody in supershift assays prevented the DNA-protein interactions formation, of the R9 sequences and nuclear proteins from amoeba, indicating that one of the proteins that interact with the R9 element is an EhEBP1-like one. In conclusion, we demonstrate that R9 motifs are recognized by an EhEBP1 protein and activate the EhPgp1 gene expression. 2012-01-01T00:00:00Z http://repositoriodigital.ipn.mx/handle/123456789/7311 Title: Nucleolin interacts with the Feline calicivirus 3’ untranslate region and the protease-polymerase NS6 and NS7 proteins, playing a role in virus replication Authors: Cancio-Lonches, Clotilde; Yocupicio-Monroy, Martha; Sandoval-Jaime, Carlos; Galván-Mendoza, Iván; Ureña, Luis; Vashist, Surender; Goodfellow, Ian; Salas-Benito, Juan Santiago; Gutiérrez-Escolano, Ana Lorena Abstract: Cellular proteins play many important roles during the life cycle of all viruses. Specifically, host cell nucleic acid-binding proteins interact with viral components of positive-stranded RNA viruses and regulate viral translation, as well as RNA replication. Here, we report that nucleolin, a ubiquitous multifunctional nucleolar shuttling phosphoprotein, interacts with the Norwalk virus and feline calicivirus (FCV) genomic 3 untranslated regions (UTRs). Nucleolin can also form a complex in vitro with recombinant Norwalk virus NS6 and -7 (NS6/7) and can be copurified with the analogous protein from feline calicivirus (p76 or NS6/7) from infected feline kidney cells. Nucleolin RNA levels or protein were not modified during FCV infection; however, as a consequence of the infection, nucleolin was seen to relocalize from the nucleoli to the nucleoplasm, as well as to the perinuclear area where it colocalizes with the feline calicivirus NS6/7 protein. In addition, antibodies to nucleolin were able to precipitate viral RNA from feline calicivirus-infected cells, indicating a direct or indirect association of nucleolin with the viral RNA during virus replication. Small interfering RNA (siRNA)-mediated knockdown of nucleolin resulted in a reduction of the cytopathic effect and virus yield in CrFK cells. Taken together, these results demonstrate that nucleolin is a nucleolar component that interacts with viral RNA and NS6/7 and is required for feline calicivirus replication Description: Artículo científico 2011-08-01T00:00:00Z http://repositoriodigital.ipn.mx/handle/123456789/7310 Title: Development of a multiplex PCR assay to detect gastroenteric pathogens in the feces of mexican children Authors: Tolentino-Ruíz, Rocío; Montoya-Varela, Diana; García-Espitia, Matilde; Salas-Benito, Mariana; Gutiérrez-Escolano, Ana Lorena; Gómez-García, María del Consuelo; Figueroa-Arredondo, Paula; Salas-Benito, Juan Santiago; De Nova-Ocampo, Mónica Abstract: Acute gastroenteritis (AGE) is a major cause of childhood morbidity and mortality worldwide; the etiology of AGE includes viruses, bacteria, and parasites.Amultiplex PCR assay to simultaneously identify human Astrovirus (HAstV), Calicivirus (HuCVs), Entamoeba histolytica (E. histolytica), and enteroinvasive Escherichia coli (EIEC) in stool samples is described. A total of 103 samples were individually analyzed by ELISA (enzyme-linked immunosorbent assays) and RT-PCR/PCR. HAstV and HuCVs were detected in four out of 103 samples (3.8 %) by RT-PCR, but ELISAs found only one sample as positive for HuCVs (2.5 %). E. histolytica was identified in two out of 19 samples (10.5 %) and EIEC in 13 out of 20 samples (70 %) by PCR, and all PCR products were sequenced to verify their identities. Our multiplex PCR results demonstrate the simultaneous amplification of different pathogens such as HAstV, EIEC, and E. histolytica in the same reaction, though the HuCVs signal was weak in every replicate. Regardless, this multiplex PCR protocol represents a novel tool for the identification of distinct pathogens and may provide support for the diagnosis of AGE in children. Description: Artículo científico 2012-10-01T00:00:00Z http://repositoriodigital.ipn.mx/handle/123456789/7309 Title: Identification of two surface proteins from C6/36 cells that bind dengue type 4 virus Authors: Salas-Benito, Juan Santiago; del Angel, Rosa María Abstract: Dengue viruses infect cells by attaching to a surface receptor, probably through the envelope (E) glycoprotein, located on the surface of the viral membrane. However, the identity of the dengue virus receptor in the mosquito and in mammalian host cells remains unknown. To identify and characterize the molecules responsible for binding dengue virus, overlay protein blot and binding assays were performed with labeled virus. Two glycoproteins of 40 and 45 kDa located on the surface of C6/36 cells bound dengue type 4 virus. Virus binding by total and membrane proteins obtained from trypsin-treated cells was inhibited, while neuraminidase treatment did not inhibit binding. Periodate treatment of cell proteins did not reduce virus binding, but it modified the molecular weight of the polypeptide detected by overlay assays. Preincubation of C6/36 cells with electroeluted 40- and 45-kDa proteins or with specific antibodies raised against these proteins inhibited virus binding. These results strongly suggest that the 40- and 45-kDa surface proteins are putative receptors or part of a receptor complex for dengue virus. Description: Artículo científico 1997-06-18T00:00:00Z