Alternative Splicing at a NAGNAG Acceptor Site as a Novel Phenotype Modifier

Approximately 30% of alleles causing genetic disorders generate premature termination codons (PTCs), which are usually associated with severe phenotypes. However, bypassing the deleterious stop codon can lead to a mild disease outcome. Splicing at NAGNAG tandem splice sites has been reported to result in insertion or deletion (indel) of three nucleotides. We identified such a mechanism as the origin of the mild to asymptomatic phenotype observed in cystic fibrosis patients homozygous for the E831X mutation (2623G>T) in the CFTR gene. Analyses performed on nasal epithelial cell mRNA detected three distinct isoforms, a considerably more complex situation than expected for a single nucleotide substitution. Structure-function studies and in silico analyses provided the first experimental evidence of an indel of a stop codon by alternative splicing at a NAGNAG acceptor site. In addition to contributing to proteome plasticity, alternative splicing at a NAGNAG tandem site can thus remove a disease-causing UAG stop codon. This molecular study reveals a naturally occurring mechanism where the effect of either modifier genes or epigenetic factors could be suspected. This finding is of importance for genetic counseling as well as for deciding appropriate therapeutic strategies

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Métier de fonctionnaire (Le)

Interventions dans le cadre des journées d’hommage à Jean Gattégno de : -Jean-Sébastien Dupuit : Jean Gattégno directeur / Michel Ricard : Terrains / Gérald Grunberg : Ce que j\u27ai appris de Jean Gattégn

Fluticasone propionate inhibits lipopolysaccharide-induced proinflammatory response in human cystic fibrosis airway grafts.

Airway inflammation, one of the major factors leading to lung damage in cystic fibrosis (CF) patients, is associated with an abnormal increase in proinflammatory cytokines. In this work, we demonstrate the increased release of the proinflammatory cytokines after lipopolysaccharide (LPS) stimulation: human interleukin (hIL)-8 in CF and non-CF airway xenografts, and hIL-6 and human growth-related oncogene-alpha (hGRO-alpha), which could be only analyzed in non-CF xenografts. Under basal conditions, we observed that hIL-8 was higher in CF xenografts compared with non-CF. We also report the anti-inflammatory effect of a glucocorticoid, fluticasone propionate (FP), on CF airway epithelium using a humanized model of airway inflammation developed in nude mice. In CF and non-CF tracheal xenografts, airway inflammation was induced by inoculating Pseudomonas aeruginosa LPS (4 h; 1 microg/ml) in the lumen of the xenografts. FP pretreatment (2 h; 10(-8) M) followed by P. aeruginosa LPS stimulation induced a significant reduction of LPS-induced hIL-8 release in airway liquid collected from CF and non-CF tracheal xenografts (85 and 80%, respectively). In non-CF tracheal xenografts, FP treatment before LPS stimulation induced a significant decrease in hIL-6 and hGRO-alpha. From these data, we suggest that FP exerts anti-inflammatory properties that may be appropriate to CF therapy, at an early stage of the disease. In addition, these results demonstrate that the humanized airway model of inflammation provides a relevant tool for analyzing the effects of anti-inflammatory drugs in different diseases in which airway inflammation is implicated

Differential expression of matrix metalloproteinases and interleukin-8 during regeneration of human airway epithelium in vivo.

In many airway diseases, the airway epithelium is severely damaged and has to regenerate rapidly to restore its function. The regeneration process involves chronological steps of epithelial cell migration, proliferation, stratification, and differentiation. The present study has used an in vivo humanized airway xenograft model in nude mice that mimics the regeneration dynamics of human airway epithelium after severe injury, and human-specific molecular tools, to study the expression profiles of epithelial matrix metalloproteinases (MMPs)-7 and -9, of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and of the pro-inflammatory cytokine interleukin-8 (IL-8) during the different steps of human airway epithelium regeneration. It was found that during the cell migration and proliferation steps, airway epithelial cells expressed IL-8 at a high level, whereas airway epithelial pseudo-stratification and surface airway epithelial differentiation were associated with increased expression of MMPs and a progressive decrease in IL-8. Interestingly, immunohistochemical analysis revealed exclusive expression of MMPs at the apical part of the well-differentiated regenerated airway epithelium, and incubation of the regenerating epithelial cells with MMP inhibitors led to abnormal epithelial differentiation. These data provide new insight into the temporal expression of MMPs and IL-8 during the regeneration of airway epithelium and demonstrate the involvement of these factors during the different steps that lead to restoration of a well-differentiated and functional airway epithelium

Journées d’hommage à Jean Gattégno. Une voix qui manque toujours

Jean Gattégno nous a quittés il y a 20 ans, le 31 mai 1994. Spécialiste de la littérature anglaise du XIXe siècle et figure importante du syndicalisme universitaire, il fut nommé en 1981, à un moment clé du développement des politiques culturelles, à la tête de la direction du livre et de la lecture. Jusqu’à son départ en 1989 (il rejoint alors l’EPBF), il y conduit avec ténacité et pertinence une politique qui restera comme une sorte d’exemple pour chacun de ces deux domaines d’intervention. Ce colloque a pour ambition non seulement d’interroger les politiques du livre aujourd’hui, 33 ans après les premières mesures dont certaines demeurent emblématiques, mais aussi de rendre hommage à cette figure d’universitaire si brillant devenu haut fonctionnaire