Repression of Human T-lymphotropic virus type 1 Long Terminal Repeat sense transcription by Sp1 recruitment to novel Sp1 binding sites

Human T-lymphotropic Virus type 1 (HTLV-1) infection is characterized by viral latency in the majority of infected cells and by the absence of viremia. These features are thought to be due to the repression of viral sense transcription in vivo. Here, our in silico analysis of the HTLV-1 Long Terminal Repeat (LTR) promoter nucleotide sequence revealed, in addition to the four Sp1 binding sites previously identified, the presence of two additional potential Sp1 sites within the R region. We demonstrated that the Sp1 and Sp3 transcription factors bound in vitro to these two sites and compared the binding affinity for Sp1 of all six different HTLV-1 Sp1 sites. By chromatin immunoprecipitation experiments, we showed Sp1 recruitment in vivo to the newly identified Sp1 sites. We demonstrated in the nucleosomal context of an episomal reporter vector that the Sp1 sites interfered with both the sense and antisense LTR promoter activities. Interestingly, the Sp1 sites exhibited together a repressor effect on the LTR sense transcriptional activity but had no effect on the LTR antisense activity. Thus, our results demonstrate the presence of two new functional Sp1 binding sites in the HTLV-1 LTR, which act as negative cis-regulatory elements of sense viral transcription.info:eu-repo/semantics/publishe

Conference highlights of the 15th international conference on human retrovirology: HTLV and related retroviruses, 4-8 june 2011, Leuven, Gembloux, Belgium

The June 2011 15th International Conference on Human Retrovirology: HTLV and Related Viruses marks approximately 30 years since the discovery of HTLV-1. As anticipated, a large number of abstracts were submitted and presented by scientists, new and old to the field of retrovirology, from all five continents. The aim of this review is to distribute the scientific highlights of the presentations as analysed and represented by experts in specific fields of epidemiology, clinical research, immunology, animal models, molecular and cellular biology, and virology

HMGA1 recruits CTIP2-repressed P-TEFb to the HIV-1 and cellular target promoters

International audienceActive positive transcription elongation factor b (P-TEFb) is essential for cellular and human im-munodeficiency virus type 1 (HIV-1) transcription elongation. CTIP2 represses P-TEFb activity in a complex containing 7SK RNA and HEXIM1. Recently, the inactive 7SK/P-TEFb small nuclear RNP (snRNP) has been detected at the HIV-1 core promoter as well as at the promoters of cellular genes, but a recruiting mechanism still remains unknown to date. Here we show global synergy between CTIP2 and the 7SK-binding chromatin master-regulator HMGA1 in terms of P-TEFb– dependent endogenous and HIV-1 gene expression regulation. While CTIP2 and HMGA1 concordingly repress the expression of cellular 7SK-dependent P-TEFb targets, the simultaneous knock-down of CTIP2 and HMGA1 also results in a boost in Tat-dependent and independent HIV-1 promoter activity. Chromatin immunoprecipitation experiments reveal a significant loss of CTIP2/7SK/P-TEFb snRNP recruitment to cellular gene promoters and the HIV-1 promoter on HMGA1 knock-down. Our findings not only provide insights into a recruiting mechanism for the inactive 7SK/P-TEFb snRNP, but may also contribute to a better understanding of viral latency

Cultural Domains and Class Structure: Assessing Homologies and Cultural Legitimacy

International audienceIt is well known that the figures representing the French social space in Distinction (Bourdieu 1979) are based on several partial analyses. This means that one of Pierre Bourdieu’s central hypotheses – the structural homology between social and cultural spaces as wholes – was not empirically tested by way of correspondence analysis (although Bourdieu did perform such an analysis for the bourgeoisie and petite bourgeoisie). Furthermore, many of the sociological discussions of cultural practices which have appeared since the publishing of Distinction use data describing a single taste domain, often music. This is beginning to change, as large-scale surveys have been conducted for Australia (Bennett et al. 1999), Norway (Rosenlund 2000), Porto in Portugal (Borges Pereira 2005), Aalborg in Denmark (Prieur et al. 2008), Great Britain (Bennett et al. 2009) – but not for France. Furthermore, as it has never been empirically tested, it is not obvious that cultural tastes constitute a homogeneous universe of practices. They can be structured by domains, depending on the relative autonomy of their respective fields of production: taste in music is not necessarily distributed in the same way as taste in books, and their relation to the social space may also differ. The French survey on cultural practices Pratiques culturelles des Français (PCF 2008), enables new implementations and tests of these hypotheses through empirical analysis

Do different approaches in population science lead to divergent or convergent models ?

This paper will first explore some of the tools for studying the dynamics that drives the trajectories: Event-duration models which lead to event history analysis; event-sequences models which lead to sequence analysis; multiple level models which lead to multilevel analysis; social network models which lead to multilevel social-network analysis. It then shows that these models can be classified under some more general concepts: The statistical individual concept covers event history and sequence analysis; the statistical network concept covers multilevel and social-network analysis. It seems then necessary to set up a more robust research program for demography. This research program may follow the induction’s way given by Bacon in searching for the structure of the studied phenomena and the interactions between the networks created by people. Such a program will be able to lead to a convergence of these different models