A coordinated phosphorylation cascade initiated by MSK1 directs RAR alpha recruitment to target gene promoters

The nuclear retinoic acid (RA) receptor alpha (RARα) is a transcriptional transregulator that controls the expression of specific gene subsets through binding at response elements and dynamic interactions with coregulators, which are coordinated by the ligand. Here, we highlighted a novel paradigm in which the transcription of RARα-target genes is controlled by phosphorylation cascades initiated by the rapid RA activation of the p38MAPK/MSK1 pathway. We demonstrate that MSK1 phosphorylates RARα at S369 located in the Ligand Binding Domain, allowing the binding of TFIIH and thereby phosphorylation of the N-terminal domain at S77 by cdk7/cyclin H. MSK1 also phosphorylates Histone H3 at S10. Finally, the phosphorylation cascade initiated by MSK1 is required for the recruitment of RARα/TFIIH complexes to response elements and subsequently for RARα target genes activation. Cancer cells characterized by a deregulated p38MAPK/MSK1 pathway, do not respond to RA, outlining the essential contribution of the RA-triggered phosphorylation cascade in RA signaling

On linearized gravity in the Randall-Sundrum scenario

In the literature about the Randall-Sundrum scenario one finds on one hand that there exist (small) corrections to Newton's law of gravity on the brane, and on another that the exact (and henceforth linearized) Einstein equations can be recovered on the brane. The explanation for these seemingly contradictory results is that the behaviour of the bulk far from the brane is different in both models. We show that explicitely in this paper.Comment: 12 pages, plain TeX, no figure

Perturbations of brane worlds

We consider cosmological models where the universe, governed by Einstein's equations, is a piece of a five dimensional double-sided anti-de Sitter spacetime (that is, a "$Z_2$-symmetric bulk") with matter confined to its four dimensional Robertson-Walker boundary or "brane". We study the perturbations of such models. We use conformally minkowskian coordinates to disentangle the contributions of the bulk gravitons and of the motion of the brane. We find the restrictions put on the bulk gravitons when matter on the brane is taken to be a scalar field and we solve in that case the brane perturbation equations.Comment: 19 pages, no figures, RevTex, version to appear in Phys.Rev.D; minor changes in chap.V, polarisation tensor at page 13 correcte

Recombinant human papillomavirus type 16 E7 protein as a model antigen to study the vaccine potential in control and E7 transgenic mice.

The early genes E6 and E7 of human papillomavirus type 16 (HPV16) are consistently and exclusively expressed in HPV16-induced cancer lesions and play major roles in the development and maintenance of the malignant phenotype. Because this protein is a good example of a tumor-associated antigen, we have used E7 as a model antigen to test the potential of an experimental vaccine as an immunotherapeutic approach. In this study, we used a murine E7-expressing tumor model (TC1 cells) to assess effects of an E7-based vaccine on tumor growth. We show that vaccination with the E7 protein, formulated in the SmithKline Beecham Biologicals proprietary adjuvants (SBAS 1 and SBAS 2), leads to the rejection of pre-established tumors. Tumor rejection was associated with the induction of a strong systemic T helper 1 response, including CTLs, and the presence of an inflammatory infiltrate within the regressing tumor. Because most identified tumor-associated antigens are self antigens rather viral antigens, we used E7 transgenic mice to evaluate the E7-based vaccine in conditions where E7 is a self antigen. Transgenic mice, which constitutively and specifically express the E7 HPV16 gene in the thyroid epithelium, rapidly develop thyroid goiters and, after several months, thyroid carcinomas. We show that E7-specific antibodies and CD4 T helper responses can be obtained by vaccinating E7 transgenic mice, although a CTL response was not detected. Despite the absence of measurable CTL responses, vaccination still reduced the growth of pre-established TC1 tumors, although less efficiently than in nontransgenic animals, but was unable to suppress or delay the development of the spontaneous thyroid pathology.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Retinoic acid and arsenic trioxide cooperate for apoptosis through phosphorylated RXR alpha.

International audienceArsenite trioxide (As2O3) induces apoptosis in several cell lines by disturbing key signal transduction pathways through its oxidative properties. Here, we report that As2O3 also induces the phosphorylation of the retinoid receptor RXRalpha, subsequent to oxidative damages and the activation of the stress-activated protein kinases cascade (JNKs). We also report that RA amplifies both As2O3-induced phosphorylation of RXRalpha and apoptosis. Taking advantage of 'rescue' F9 cell lines expressing RXRalpha mutated at its phosphorylation sites, in an RXRalpha null background, we provide evidence that RXRalpha is a key element involved in that potentiating effect. Finally, we demonstrate that As2O3 also abrogates the transactivation of RA-target genes

SUG-1 plays proteolytic and non-proteolytic roles in the control of retinoic acid target genes via its interaction with SRC-3.

International audienceNuclear retinoic acid receptor alpha (RARalpha) activates gene expression through dynamic interactions with coregulatory protein complexes, the assembly of which is directed by the ligand and the AF-2 domain of RARalpha. Then RARalpha and its coactivator SRC-3 are degraded by the proteasome. Recently it has emerged that the proteasome also plays a key role in RARalpha-mediated transcription. Here we show that SUG-1, one of the six ATPases of the 19 S regulatory complex of the 26 S proteasome, interacts with SRC-3, is recruited at the promoters of retinoic acid (RA) target genes, and thereby participates to their transcription. In addition, SUG-1 also mediates the proteasomal degradation of SRC-3. However, when present in excess amounts, SUG-1 blocks the activation of RARalpha target genes and the degradation of RARalpha that occurs in response to RA, via its ability to interfere with the recruitment of SRC-3 and other coregulators at the AF-2 domain of RARalpha. We propose a model in which the ratio between SUG-1 and SRC-3 is crucial for the control of RARalpha functioning. This study provides new insights into how SUG-1 has a unique role in linking the transcription and degradation processes via its ability to interact with SRC-3