Making Sense out of Antisense Transcription in Human T-Cell Lymphotropic Viruses (HTLVs)

Retroviral gene expression generally depends on a full-length transcript that initiates in the 5′ long terminal repeat (LTR), which is either unspliced or alternatively spliced. We and others have demonstrated the existence of an antisense transcript initiating in the 3′ LTR of the Human T-cell Leukemia Virus type 1 (HTLV-1) that is involved in the production of HBZ (HTLV-1 basic leucine zipper (bZIP) factor). HBZ is a Fos-like factor capable of inhibiting Tax-mediated activation of the HTLV-1 LTR by interacting with the cellular transcription factor cAMP-response element-binding protein (CREB) and the pleiotropic cellular coactivators p300/CBP. HBZ can also activate cellular transcription through its interaction with p300/CBP. Interestingly, HBZ has also been found to promote T-lymphocyte proliferation. By down-regulating viral expression and by stimulating T-cell proliferation, HBZ could be essential in the establishment of a chronic infection. Antisense transcription also occurs in the closely related HTLV-2 retrovirus as well as in the recently discovered HTLV-3 and HTLV-4. These antisense transcripts are also involved in the production of retroviral proteins that we have termed Antisense Protein of HTLVs (APH). Like HBZ, the APH proteins are localized in the nucleus of transfected cells and repress Tax-mediated viral transcription

Prospectives

Tiré de: Prospectives, vol. 1, no 2, avril 1965Titre de l'écran-titre (visionné le 24 janv. 2013

Florian Sauvageau, Simon Thibault, Pierre Trudel, dirs, Les Fausses Nouvelles, nouveaux visages, nouveaux défis. Comment déterminer la valeur de l’information dans les sociétés démocratiques ?

L’ouvrage Les Fausses Nouvelles, nouveaux visages, nouveaux défis dirigé par un trio composé de Florian Sauvageau, Simon Thibault et Pierre Trudel est la publication d’un séminaire tenu à l’université de Montréal par le Centre d’études sur les médias à l’automne 2017. Il s’intéresse aux « fakes news » ou, à tout le moins, à une certaine conception de cette expression qui, autant en anglais qu’en français, serait à proscrire, au profit de « désinformation », en raison de ses controverses polit..

Jean-Marie Charon, Jacqueline Papet, dirs, Le Journalisme en questions. Réponses internationales

Dirigé par Jean-Marie Charon et Jacqueline Papet, Le journalisme en questions. Réponses internationales se veut les actes de la quatrième édition de la Conférence nationale des métiers du journalisme tenu en septembre 2013 à Paris. La volonté de cette conférence est de « sortir du prisme purement français » (p. 7) pour trouver des réponses ailleurs sur la planète aux questions qui bouleversent la presse en France. Celles et ceux qui étaient présents à ces deux journées se rappelleront de l’am..

Jean-Marie Charon, Jacqueline Papet, dirs, Le Journalisme en questions. Réponses internationales

Dirigé par Jean-Marie Charon et Jacqueline Papet, Le journalisme en questions. Réponses internationales se veut les actes de la quatrième édition de la Conférence nationale des métiers du journalisme tenu en septembre 2013 à Paris. La volonté de cette conférence est de « sortir du prisme purement français » (p. 7) pour trouver des réponses ailleurs sur la planète aux questions qui bouleversent la presse en France. Celles et ceux qui étaient présents à ces deux journées se rappelleront de l’am..

La transformation du blogue en une activité du journalisme professionnel québécois francophone (1995-2010)

L’objectif de cette recherche consiste à dévoiler les adaptations qu’a subies la pratique discursive du blogue, née hors des médias traditionnels, en devenant une activité journalistique professionnelle des médias québécois francophones. La recherche a été menée selon une approche méthodologique de type qualitative avec trois méthodes – une revue de presse, une observation de blogues et des entrevues auprès de journalistes-animateurs de blogues professionnels. Les résultats montrent que les entreprises médiatiques ont, par diverses retouches, transformé le blogue d’un espace pour la liberté d’expression individuelle, ce qu’il était à l’origine, en un espace d’expression d’opinion sous contrôle organisationnel. Elles indiquent aussi que le souhait formulé par les médias que le blogue soit le moyen par excellence du dialogue entre les journalistes et le public, ne s’est que très peu réalisé. Dans ce mémoire, le processus d’appropriation et d’adaptation par les médias d’une forme de discours née hors du journalisme professionnel est examiné sous l’éclairage croisé du "flou" qui serait la caractéristique principale du journalisme selon Denis Ruellan, et sous celui de la tendance au "journalisme de communication", modélisé par Jean Charon et Jean de Bonville

Pseudomonas aeruginosa isolates from dental units waterlines can be divided in two distinct groups, including one displaying phenotypes similar to isolates from cystic fibrosis patients.

Pseudomonas aeruginosa displays broad genetic diversity, giving it an astonishing capacity to adapt to a variety of environments and to infect a wide range of hosts. While many P. aeruginosa isolates of various origins have been analyzed, isolates from cystic fibrosis (CF) patients have received the most attention. Less is known about the genetic and phenotypic diversity of P. aeruginosa isolates that colonize other environments where flourishing biofilms can be found. In the present study, 29 P. aeruginosa isolates from dental unit waterlines and CF patients were collected and their genetic and phenotypes profiles were compared to determine whether environmental and clinical isolates are related. The isolates were first classified using the random amplified polymorphic DNA method. This made it possible to distribute the isolates into one clinical cluster and two environmental clusters. The isolates in the environmental cluster that were genetically closer to the clinical cluster also displayed phenotypes similar to the clinical isolates. The isolates from the second environmental cluster displayed opposite phenotypes, particularly an increased capacity to form biofilms. The isolates in this cluster were also the only ones harboring genes that encoded specific epimerases involved in the synthesis of lipopolysaccharides, which could explain their increased ability to form biofilms. In conclusion, the isolates from the dental unit waterlines could be distributed into two clusters, with some of the environmental isolates resembled the clinical isolates. Keywords: Pseudomonas aeruginosa, cluster, RAPD, elastase, biofilm, Dictyostelium discoideum, cell lysi

A modified version of a Fos-associated cluster in HBZ affects Jun transcriptional potency

Like c-Fos, HBZ (HTLV-I bZIP factor) is able to interact with c-Jun but differs considerably from c-Fos in its ability to activate AP-1-responsive genes since HBZ rather inhibits transcriptional activity of c-Jun. To better understand the molecular mechanisms involved in this down-regulation of c-Jun activity, a large number of HBZ/c-Fos chimeras was constructed and analyzed for their ability to interact with c-Jun, to bind to the AP-1 motif and to stimulate expression of a reporter gene containing the collagenase promoter. By this approach, we demonstrate that the DNA-binding domain of HBZ is responsible for its inhibitory effect on the trans-activation potential of c-Jun. However, unexpectedly, we found that exchange of a cluster of six charged amino acids immediately adjacent to the DNA contact region altered significantly transcriptional activity of chimeras. This particular subdomain could be involved in efficient presentation of the AP-1 complex to the transcriptional machinery. To confirm this role, specific residues present in the cluster of HBZ were substituted for corresponding amino acids in c-Fos. Unlike the JunD-activating potential of wild-type HBZ, this mutant was no longer able to stimulate JunD activity, confirming the key role of this particular cluster in regulation of Jun transcriptional potency

JunD/HBZ enhances HBZ enhances HTLV-1 antisense transcription

Infection with the human T-cell leukemia virus type 1 (HTLV-1) results in a variety of diseases including adult T-cell leukemia (ATL), a fatal malignancy characterized by the uncontrolled proliferation of virally infected CD4+ T cells. The HTLV-1 basic leucine zipper factor (HBZ) is believed to contribute to development and maintenance of ATL. Unlike the other HTLV-1 genes, the hbz gene is encoded on the complementary strand of the provirus and therefore is not under direct control of the promoter within the 5′ long terminal repeat (LTR) of the provirus. This promoter can undergo inactivating genetic or epigenetic changes during the course of ATL that eliminates expression of all viral genes except that of hbz. In contrast, repressive modifications are not known to occur on the hbz promoter located in the 3′ LTR, and hbz expression has been consistently detected in all ATL patient samples. Although Sp1 regulates basal transcription from the HBZ promoter, other factors that activate transcription remain undefined. In this study, we used a proviral reporter construct deleted of the 5′ LTR to show that HBZ upregulates its own expression through cooperation with JunD. Activation of antisense transcription was apparent in serum-deprived cells in which the level of JunD was elevated, and elimination of JunD expression by gene knockout or shRNA-mediated knockdown abrogated this effect. Activation through HBZ and JunD additionally required Sp1 binding at the hbz promoter. These data favor a model in which JunD is recruited to the promoter through Sp1, where it heterodimerizes with HBZ thereby enhancing its activity. Separately, hbz gene expression led to an increase in JunD abundance, and this effect correlated with emergence of features of transformed cells in immortalized fibroblasts. Overall, our results suggest that JunD represents a novel therapeutic target for the treatment of ATL