Études des mécanismes de régulation de la transcription des gènes humains P21CIP1/WAF1, GPC3 (GLYPICAN 3) et AβPP (AMYLOID β-PRECURSOR PROTEIN)

La connaissance des mécanismes qui contrôlent la transcription des gènes, comme l’interaction de facteurs protéiques au niveau des promoteurs, est essentielle pour comprendre plusieurs fonctions biologiques et espérer traiter certaines pathologies. Nous nous sommes attardés à mieux comprendre les mécanismes qui régulent trois gènes humains dont les patrons d’expression sont différents et qui sont impliqués dans diverses pathologies en tentant de mettre en parallèle les différences structurales et fonctionnelles entre ceux-ci. Les gènes AβPP et p21 sont exprimés chez l’adulte alors que GPC3 est exprimé uniquement chez l’embryon de façon spécifique aux tissus. L’expression d’AβPP est aussi spécifique aux tissus et sa surexpression fait partie des mécanismes mis en cause chez les patients atteints de la maladie d’Alzheimer et du syndrome de Down. Le gène p21 est quant à lui exprimé dans plusieurs types cellulaires et est fortement induit suite à des dommages à l’ADN. Enfin, nous avons montré que GPC3 est exprimé de manière différentielle dans le neuroblastome (NB) et la tumeur de Wilms (WT), deux tumeurs embryonnaires. p21 : La caractérisation du promoteur proximal de p21 dans les fibroblastes humains normaux en prolifération nous a permis de localiser sept empreintes protéiques dont une au niveau de la séquence consensus pour NFI. Les études de retard sur gel, de transfection transitoire, d’immunoprécipitation de la chromatine et d’anti-ARN ont permis de confirmer la liaison de NFI et de le définir comme répresseur important de la transcription de p21. AβPP : Nous avons montré que USF et Sp1 se lient au promoteur de AβPP et que leur liaison est essentielle pour générer une activité maximale du promoteur. La caractérisation in cellulo du promoteur dans les neurones et les astrocytes normaux a révélé huit sites d’interaction ADN-protéine, entre-autres au niveau des sites de liaison des facteurs de transcription CTCF, USF et Sp1. GPC3 : La caractérisation du promoteur de GPC3 nous a permis de montrer 1) une struture chromatinienne particulière tout le long du promoteur et 2) plusieurs empreintes protéiniques putatives dont certaines spécifiques à la lignée SJNB-7 qui exprime GPC3. Parmi ces dernières, nous avons mis en évidence la liaison possible d’un facteur de transcription de type NF-Y.Gene transcription is the first step to the production of any given protein. Understanding of the molecular mechanisms regulating gene expression, such as the binding of transcription factors to genes promoters, is essential to the understanding of biological functions and to develop new powerful therapies against many clinically documented pathologies. We investigated the transcriptional regulatory mechanisms of three human genes very differently expressed and involved in diverse pathologies in an attempt to reveal structurals and functionals differencies between these mechanisms. AβPP and p21 genes are both expressed in adult while GPC3 is only transcribed in a tissus specific manner before birth. The expression of the AβPP gene is also specific to tissue and its over-expression may be involved in Alzheimer disease and Down syndrome. P21 gene is expressed in many types of cells and is strongly induced by DNA damage. Finally, we demonstrated that GPC3 is differently expressed in neuroblastoma and Wilms' tumor. P21 : The characterization of the proximal promoter from the p21 gene in normal human proliferating fibroblasts revealed seven DNA-protein footprints of which one bears a perfect consensus sequence for the NFI family of transcription factors. EMSA, CHIP, anti-RNA and transient transfection of recombinant constructs analyses clearly demonstrated that NFI interact with the most proximal LMPCR footprint on the p21 promoter and functions as a repressor. Upon serum starvation, a change in the electrophoretic mobility of the NFI DNA-protein complex was observed that may contribute to the activation mechanistic of the p21 gene throughout cell senescence and differentiation. AβPP : We demonstrated that Sp1, like USF, recognizes an element in the human AβPP gene that is necessary for full promoter activity. In cellulo footprinting analysis revealed at least eight DNA-protein interactions including CTCF, USF and many Sp1 target sites. These results were further supported by EMSA and transient transfection analysis. GPC3 : The characterisation of the entire GPC3 gene promoter revealed 1) a particular DNA structure in the promoter and 2) eight large protected regions. The use of competitor oligos in EMSA experiments and super-shift assays showed that an NFY-type transcription factor (TF) may explain the GPC3 aberrant expression in SJNB-7

Application of a new method in the study of pelvic floor muscle passive properties in continent women

The aim of this study was to present a new methodology for evaluating the pelvic floor muscle (PFM) passive properties. The properties were assessed in 13 continent women using an intra-vaginal dynamometric speculum and EMG (to ensure the subjects were relaxed) in four different conditions: (1) forces recorded at minimal aperture (initial passive resistance); (2) passive resistance at maximal aperture; (3) forces and passive elastic stiffness (PES) evaluated during five lengthening and shortening cycles; and (4) percentage loss of resistance after 1 min of sustained stretch. The PFMs and surrounding tissues were stretched, at constant speed, by increasing the vaginal antero-posterior diameter; different apertures were considered. Hysteresis was also calculated. The procedure was deemed acceptable by all participants. The median passive forces recorded ranged from 0.54 N (interquartile range 1.52) for minimal aperture to 8.45 N (interquartile range 7.10) for maximal aperture while the corresponding median PES values were 0.17 N/mm (interquartile range 0.28) and 0.67 N/mm (interquartile range 0.60). Median hysteresis was 17.24 N∗mm (interquartile range 35.60) and the median percentage of force losses was 11.17% (interquartile range 13.33). This original approach to evaluating the PFM passive properties is very promising for providing better insight into the patho-physiology of stress urinary incontinence and pinpointing conservative treatment mechanisms

Association between recreational screen time and sleep quality among adolescents during the third wave of the COVID-19 pandemic in Canada

The study objective was to verify whether recreational screen time was associated with sleep quality among adolescents during the third wave of the COVID-19 pandemic in Canada. Data collection took place in four high schools in the region of Chaudière-Appalaches (Quebec, Canada) from the end of April to mid-May 2021. Recreational screen time and sleep quality were measured using the French versions of validated questionnaires specifically designed for adolescents. A total of 258 adolescents (14–18 years; 66.3% girls) answered the online survey. Adolescent boys had a higher total mean recreational screen time (454.3 ± 197.5 vs. 300.5 ± 129.3 min/day, p < 0.0001) and a higher total mean sleep quality score (4.2 ± 0.9 vs. 3.9 ± 0.8, p = 0.0364) compared to girls. Recreational screen time (β = −0.0012, p = 0.0005) and frequency of concurrent screen use (sometimes: β = −0.3141, p = 0.0269; often: β = −0.4147, p = 0.0048; almost always or always: β = −0.6155, p = 0.0002) were negatively associated with sleep quality while being a boy (β = 0.4276, p = 0.0004) was positively associated with sleep quality and age (p = 0.6321) was not. This model explained 16% of the variance in adolescents’ sleep quality. Public health interventions during and after the COVID-19 pandemic should target recreational screen time, concurrent screen use and especially girls to possibly improve sleep quality and promote adolescents’ physical and mental health

Psychosocial correlates of recreational screen time among adolescents

The study objective was to identify the psychosocial correlates of recreational screen time among adolescents. Data collection took place in four high schools from the Chaudière-Appalaches region (Quebec, Canada) from late April to mid-May 2021. A total of 258 French-speaking adolescents (69.8% between 15 and 16 years and 66.3% girls) answered an online questionnaire based on the Reasoned Action Approach. Recreational screen time was measured using the French version of a validated questionnaire. Adolescents reported a mean of 5 h and 52 min/day of recreational screen time. Recreational screen time was associated with being a boy (β = 0.33; p < 0.0001) and intention to limit recreational screen time to a maximum of 2 h/day (β = −0.15; p = 0.0001); this model explained 30% of the variance in behavior. Intention to limit recreational screen time to a maximum of 2 h/day in the next month was associated with attitude (β = 0.49; p < 0.0001), self-identity (β = 0.33; p < 0.0001), being a boy (β = −0.21; p = 0.0109), perceived behavioral control (β = 0.18; p = 0.0016), and injunctive norm (β = 0.17; p < 0.0001); this model explained 70% of the variance in intention. This study identified avenues to design public health interventions aimed at lowering recreational screen time among this population

Organocatalytic Transfer Hydrogenation of Cyclic Enones

The first enantioselective organocatalytic transfer hydrogenation of cyclic enones has been accomplished. The use of iminium catalysis has provided a new organocatalytic strategy for the enantioselective reduction of β,β-substituted α,β-unsaturated cycloalkenones, to generate β-stereogenic cyclic ketones. The use of imidazolidinone 4 as the asymmetric catalyst has been found to mediate the hydrogenation of a large class of enone substrates with tert-butyl Hantzsch ester serving as an inexpensive source of hydrogen. The capacity of catalyst 4 to enable enantioselective transfer hydrogenation of cycloalkenones has been extended to five-, six-, and seven-membered ring systems. The sense of asymmetric induction is in complete accord with the stereochemical model first reported in conjunction with the use of catalyst 4 for enantioselective ketone Diels−Alder reactions

Responsiveness and clinical utility of the geriatric self-efficacy index for urinary incontinence

OBJECTIVES: To report on the responsiveness testing and clinical utility of the 12-item Geriatric Self-Efficacy Index for Urinary Incontinence (GSE-UI). DESIGN: Prospective cohort study. SETTING: Six urinary incontinence (UI) outpatient clinics in Quebec, Canada. PARTICIPANTS: Community-dwelling incontinent adults aged 65 and older. MEASUREMENTS: The abridged 12-item GSE-UI, measuring older adults' level of confidence for preventing urine loss, was administered to all new consecutive incontinent patients 1 week before their initial clinic visit, at baseline, and 3 months posttreatment. At follow-up, a positive rating of improvement in UI was ascertained from patients and their physicians using the Patient's and Clinician's Global Impression of Improvement scales, respectively. Responsiveness of the GSE-UI was calculated using Guyatt's change index. Its clinical utility was determined using receiver operating curves. RESULTS: Eighty-nine of 228 eligible patients (39.0%) participated (mean age 72.6+5.8, range 65–90). At 3-month follow-up, 22.5% of patients were very much better, and 41.6% were a little or much better. Guyatt's change index was 2.6 for patients who changed by a clinically meaningful amount and 1.5 for patients having experienced any level of improvement. An improvement of 14 points on the 12-item GSE-UI had a sensitivity of 75.1% and a specificity of 78.2% for detecting clinically meaningful changes in UI status. Mean GSE-UI scores varied according to improvement status (P<.001) and correlated with changes in quality-of-life scores (r=0.7, P<.001) and reductions in UI episodes (r=0.4, P=.004). CONCLUSION: The GSE-UI is responsive and clinically useful

A multi-informant and multi-polygenic approach to understanding predictors of peer victimisation in childhood and adolescence

Introduction Peer victimisation is a prevalent occurrence in childhood and adolescence and can often have long-lasting consequences. Previous research using polygenic scores (PGSs) have revealed various genetic vulnerabilities as predictive of victimisation in childhood. However, findings were based on self-report and may therefore be influenced by varying self-perceptions. Previous investigations also focused on average victimisation across childhood, and thus do not capture variability in polygenic predictability over time. The present study, therefore, aimed to investigate associations between PGSs and victimisation using separate and combined reports from teachers and peers in childhood, as well as self-reports in later adolescence to explore trajectories of victimisation. Methods Data were derived from the Quebec Newborn Twin Study. Participants were assessed for victimisation using self-reports from 7 to 17 years and using teacher ratings and peer nominations between 7 and 10 years (n = 536). Ten PGSs related to mental health, cognitive abilities and physical traits were examined as possible predictors of victimisation using linear regressions and growth curve models. Results Findings revealed that PGSs associated with victimisation are consistent across informants, but to varying extent according to estimated effect sizes. Self-reported victimisation was predicted by PGSs related to mental health, while PGSs related to cognitive and physical traits had larger effect estimates when predicting teacher- and peer-reported victimisation. The PGS for educational attainment was consistently negatively associated with victimisation across informants, producing the largest effect estimates (β = −.104, 95% CI = −.169 to −.039) when predicting a multi-informant measure of victimisation. No PGS predicted changes in victimisation over time. Conclusion While the PGS for educational attainment is a robust predictor of victimisation, many PGSs are differentially associated with victimisation depending on the informant. Such findings highlight the need to pay close attention to the phenotypic assessment of victimisation, and show that using multiple informants can both strengthen and provide unique insight into how associations may occur

Introduction

Ouellet Richard, Paquin Stéphane. Introduction. In: Revue Québécoise de droit international, Hors-série mars 2022 – L’Accord Canada-États-Unis-Mexique. pp. 1-3