Species-specific regulation of XIST by the JPX/FTX orthologs.

X chromosome inactivation (XCI) is an essential process, yet it initiates with remarkable diversity in various mammalian species. XIST, the main trigger of XCI, is controlled in the mouse by an interplay of lncRNA genes (LRGs), some of which evolved concomitantly to XIST and have orthologues across all placental mammals. Here, we addressed the functional conservation of human orthologues of two such LRGs, FTX and JPX.

A primate-specific retroviral enhancer wires the XACT lncRNA into the core pluripotency network in humans.

Transposable elements (TEs) have been proposed to play an important role in driving the expansion of gene regulatory networks during mammalian evolution, notably by contributing to the evolution and function of long non-coding RNAs (lncRNAs). XACT is a primate-specific TE-derived lncRNA that coats active X chromosomes in pluripotent cells and may contribute to species-specific regulation of X-chromosome inactivation. Here we explore how different families of TEs have contributed to shaping the XACT locus and coupling its expression to pluripotency.

The Ftx Noncoding Locus Controls X Chromosome Inactivation Independently of Its RNA Products.

Accumulation of the Xist long noncoding RNA (lncRNA) on one X chromosome is the trigger for X chromosome inactivation (XCI) in female mammals. Xist expression, which needs to be tightly controlled, involves a cis-acting region, the X-inactivation center (Xic), containing many lncRNA genes that evolved concomitantly to Xist from protein-coding ancestors through pseudogeneization and loss of coding potential. Here, we uncover an essential role for the Xic-linked noncoding gene Ftx in the regulation of Xist expression.

XACT Noncoding RNA Competes with XIST in the Control of X Chromosome Activity during Human Early Development.

Sex chromosome dosage compensation is essential in most metazoans, but the developmental timing and underlying mechanisms vary significantly, even among placental mammals. Here we identify human-specific mechanisms regulating X chromosome activity in early embryonic development. Single-cell RNA sequencing and imaging revealed co-activation and accumulation of the long noncoding RNAs (lncRNAs) XACT and XIST on active X chromosomes in both early human pre-implantation embryos and naive human embryonic stem cells.

Early Transcriptome Signatures from Immunized Mouse Dendritic Cells Predict Late Vaccine-Induced T-Cell Responses.

Systems biology offers promising approaches for identifying response-specific signatures to vaccination and assessing their predictive value. Here, we designed a modelling strategy aiming to predict the quality of late T-cell responses after vaccination from early transcriptome analysis of dendritic cells. Using standardized staining with tetramer, we first quantified antigen-specific T-cell expansion 5 to 10 days after vaccination with one of a set of 41 different vaccine vectors all expressing the same antigen.

Efficacy of DNA vaccines forming e7 recombinant retroviral virus-like particles for the treatment of human papillomavirus-induced cancers.

Human papillomavirus (HPV) is involved in the development of anogenital tumors and also in the development of oropharyngeal head and neck carcinomas, where HPV-16, expressing the E6 and E7 oncoproteins, is the most frequent serotype. Although vaccines encoding L1 and L2 capsid HPV proteins are efficient for the prevention of HPV infection, they are inadequate for treating established tumors. Hence, development of innovative vaccine therapies targeting E6/E7 is important for controlling HPV-induced cancers.

XACT, a long noncoding transcript coating the active X chromosome in human pluripotent cells.

X-chromosome inactivation (XCI) in mammals relies on XIST, a long noncoding transcript that coats and silences the X chromosome in cis. Here we report the discovery of a long noncoding RNA, XACT, that is expressed from and coats the active X chromosome specifically in human pluripotent cells. In the absence of XIST, XACT is expressed from both X chromosomes in humans but not in mice, suggesting a unique role for XACT in the control of human XCI initiation.

Recombinant retrovirus-derived virus-like particle-based vaccines induce hepatitis C virus-specific cellular and neutralizing immune responses in mice.

While the immunological correlates of hepatitis C virus (HCV)-specific immunity are not well understood, it is now admitted that an effective vaccine against HCV will need to induce both cellular and humoral immune responses and address viral heterogeneity to prevent immune escape. We developed a vaccine platform specifically aimed at inducing such responses against HCV antigens displayed by recombinant retrovirus-based virus-like particles (VLPs) made of Gag of murine leukemia virus. Both ex vivo produced VLPs and plasmid DNA encoding VLPs can be used as vaccines.

DNA vaccines expressing retrovirus-like particles are efficient immunogens to induce neutralizing antibodies.

We aimed at improving DNA vaccination efficiency for inducing neutralizing antibodies. We used plasmids encoding Gag of MLV and envelope proteins of VSV or WNV. Upon in vivo injection, they generate retrovirus-derived VLPs pseudotyped with these envelopes expressed in their wild-type conformation.

Recombinant retrovirus-like particle forming DNA vaccines in prime-boost immunization and their use for hepatitis C virus vaccine development.

Background: The expression of Moloney murine leukemia virus (Mo-MLV) gag proteins is sufficient to generate retrovirus-like particles (retroVLPs) that can be used as antigen-display platforms by pseudotyping with heterologous envelope proteins or by insertion of epitopes in structural constituents. To circumvent the in vitro production of such retroVLPs, we used DNA plasmids generating recombinant retroVLPs (plasmo-retroVLPs) as immunogens. We previously demonstrated that plasmo-retroVLPs induce significantly better antigen-specific T cell responses and antiviral immune protection than plasmids bearing a single mutation preventing retroVLPs assembly.