Du mécanisme moléculaire de la résistance hormonale à la tumorigénèse dans la maladie de Cushing

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Strange bedfellows? Attitudes toward minority religious symbols in the public sphere

In this study, we contend that distinguishing individuals who support bans on minority religious symbols from those who want to ban all religious symbols improves our understanding of the roots of opposition to minority religious symbols in the public sphere. We hypothesize that both groups are likely driven by markedly different motivations and that opposition to the presence of minority religious symbols in the public sphere may be the result of an alliance between “strange bedfellows,” clusters of individuals whose political outlooks usually bring them to opposite sides of political debates. Drawing on a survey conducted in the province of Quebec (Canada), we find that while holding liberal values and low religiosity are key characteristics of those who would ban all religious symbols, feelings of cultural threat and generalized prejudice are central characteristics of those who would only restrict minority religious symbols. Negative attitudes specifically toward Muslims, however, also appear to motivate both groups

Effects of a peer support programme for youth social services employees experiencing potentially traumatic events: a protocol for a prospective cohort study

Introduction The use of peer support programmes to help workers experiencing potentially traumatic events (PTE) has increased in high-risk organisations in the last decades. However, the scientific evidence of its effectiveness is still very limited. This paper aims to describe the protocol of a prospective cohort study that assesses the efficacy of a peer support programme among youth social services employees exposed to a PTE at work on psychological well-being, work functioning and needs of support. Methods and analysis This is a mixed-methods prospective study that will examine workers' evolution four times over a 12-month period in Canada. This study involves: (1) quantitative data obtained through selfadministrated questionnaires among 222 workers, and (2) qualitative in-depth interviews with a subsample of 45 workers. This study will compare findings from a cohort who received the support of a peer following a PTE (peer support–experimental protocol) as part of the experimental protocol of the Montreal Youth Social Services-University Institute (MYSS-UI), the second group of workers did not ask for the peer support (no peer support-experimental protocol) but was part of MYSS-UI, and the third group received standard organisational support from the Monteregie Youth Social Services (MYSS) (standard organisational protocol). Ethics and dissemination The protocol and informed consent form complied with the ethics guidelines of the MYSS-UI. The Research Ethics Board of MYSS-UI and MYSS reviewed and accepted the protocol as required. The results of the study will be published in peerreviewed journals, presented at research and general public conferences, disseminated via a public report for the institute that funded the project and for all workers. Results of this study will influence decision making regarding intervention policies following PTE and peer support interventions may be expanded throughout the youth social services in Canada and worldwide

Mediator and cohesin connect gene expression and chromatin architecture

Transcription factors control cell-specific gene expression programs through interactions with diverse coactivators and the transcription apparatus. Gene activation may involve DNA loop formation between enhancer-bound transcription factors and the transcription apparatus at the core promoter, but this process is not well understood. Here we report that mediator and cohesin physically and functionally connect the enhancers and core promoters of active genes in murine embryonic stem cells. Mediator, a transcriptional coactivator, forms a complex with cohesin, which can form rings that connect two DNA segments. The cohesin-loading factor Nipbl is associated with mediator–cohesin complexes, providing a means to load cohesin at promoters. DNA looping is observed between the enhancers and promoters occupied by mediator and cohesin. Mediator and cohesin co-occupy different promoters in different cells, thus generating cell-type-specific DNA loops linked to the gene expression program of each cell.National Institutes of Health (U.S.) (Fellowship)Canadian Institutes of Health Research (Research Fellowship)National Institutes of Health (U.S.) (Grant R01 HG002668

Distinct Developmental Roles of Cell Cycle Inhibitors p57Kip2 and p27Kip1 Distinguish Pituitary Progenitor Cell Cycle Exit from Cell Cycle Reentry of Differentiated Cells▿ †

Patterning and differentiation signals are often believed to drive the developmental program, including cell cycle exit of proliferating progenitors. Taking advantage of the spatial and temporal separation of proliferating and differentiated cells within the developing anterior pituitary gland, we investigated the control of cell proliferation during organogenesis. Thus, we identified a population of noncycling precursors that are uniquely marked by expression of the cell cycle inhibitor p57Kip2 and by cyclin E. In p57Kip2−/− mice, the developing pituitary is hyperplastic due to accumulation of proliferating progenitors, whereas overexpression of p57Kip2 leads to hypoplasia. p57Kip2-dependent cell cycle exit is not required for differentiation, and conversely, blockade of cell differentiation, as achieved in Tpit−/− pituitaries, does not prevent cell cycle exit but rather leads to accumulation of p57Kip2-positive precursors. Upon differentiation, p57Kip2 is replaced by p27Kip1. Accordingly, proliferating differentiated cells are readily detected in p27Kip1−/− pituitaries but not in wild-type or p57Kip2−/− pituitaries. Strikingly, all cells of p57Kip2−/−;p27Kip1−/− pituitaries are proliferative. Thus, during normal development, progenitor cell cycle exit is controlled by p57Kip2 followed by p27Kip1 in differentiated cells; these sequential actions, taken together with different pituitary outcomes of their loss of function, suggest hierarchical controls of the cell cycle that are independent of differentiation

BioDiscViz: A visualization support and consensus signature selector for BioDiscML results.

Machine learning (ML) algorithms are powerful tools to find complex patterns and biomarker signatures when conventional statistical methods fail to identify them. While the ML field made significant progress, state of the art methodologies to build efficient and non-overfitting models are not always applied in the literature. To this purpose, automatic programs, such as BioDiscML, were designed to identify biomarker signatures and correlated features while escaping overfitting using multiple evaluation strategies, such as cross validation, bootstrapping and repeated holdout. To further improve BioDiscML and reach a broader audience, better visualization support and flexibility in choosing the best models and signatures are needed. Thus, to provide researchers with an easily accessible and usable tool for in depth investigation of the results from BioDiscML outputs, we developed a visual interaction tool called BioDiscViz. This tool provides summaries, tables and graphics, in the form of Principal Component Analysis (PCA) plots, UMAP, t-SNE, heatmaps and boxplots for the best model and the correlated features. Furthermore, this tool also provides visual support to extract a consensus signature from BioDiscML models using a combination of filters. BioDiscViz will be a great visual support for research using ML, hence new opportunities in this field by opening it to a broader community

SetDB1 contributes to repression of genes encoding developmental regulators and maintenance of ES cell state

Transcription factors that play key roles in regulating embryonic stem (ES) cell state have been identified, but the chromatin regulators that help maintain ES cells are less well understood. A high-throughput shRNA screen was used to identify novel chromatin regulators that influence ES cell state. Loss of histone H3 Lys 9 (H3K9) methyltransferases, particularly SetDB1, had the most profound effects on ES cells. Chromatin immunoprecipitation (ChIP) coupled with massively parallel DNA sequencing (ChIP-Seq) and functional analysis revealed that SetDB1 and histone H3K9-methylated nucleosomes occupy and repress genes encoding developmental regulators. These SetDB1-occupied genes are a subset of the “bivalent” genes, which contain nucleosomes with H3K4me3 (H3K4 trimethylation) and H3K27me3 modifications catalyzed by Trithorax and Polycomb group proteins, respectively. These genes are subjected to repression by both Polycomb group proteins and SetDB1, and loss of either regulator can destabilize ES cell state