0343 : Essential role of P2Y6 UDP receptor in Angiotensin-II dependent arterial hypertension

Extracellular nucleotides are responsible for pleiotropic effects in the vasculature. Uracyl nucleotides are vasoactive and trophic agents and promote inflammation. The participation of specific P2 receptors in these effects remains undefined and their potential contribution in arterial hypertension is unknown.ObjectiveTo evaluate the contribution of the UDP receptor P2Y6 in hypertension in mouse.MethodsArterial contraction was evaluated using a wire myograph. Blood pressure was measured following nucleotides iv infusion and experimental hypertension was induced either by Angiotensine-II (Ang-II 1mg/kg/j) or DOCA-salt (1%) in uni-nephrectomized mice. Histological approaches, immunofluorescence and RTqPCR were used to evaluate the nature of vascular remodeling.ResultsP2Y6 displayed the highest arterial expression level among other P2Y receptors. Contraction of conductance (thoracic aorta) and resistance (mesenteric) arteries was abrogated in P2ry6-/- mice in response to UDP and UTP while other vasoconstrictor induced normal responses. P2Y6 receptor triggered a moderated intracellular calcium increase while RhoA (calcium facilitating pathway) activation was abrogated in P2ry6-/- mice. Both genetic deletion and pharmacological blockade of P2Y6 receptor abolished Ang-II-induced blood pressure increase (40 mmHg in wild type mice). By contrast, hypertensive response in DOCA-salt was equivalent in both genotypes. Following Ang-II treatment, P2ry6-/- mice developed a reduced arterial hypertrophic remodeling and fibrosis but equivalent immune cell recruitment/infiltration compared to wild type. These changes were corroborated to reduced mRNA expressions of TGFβ and NADPH oxidase subunits.ConclusionsVascular P2Y6 receptor contributes to exaggerated vascular tone, hypertrophy and fibrosis in the context of Ang-II-dependent hypertension. Its absence or pharmacological blockade limits vascular damages and prevents blood pressure increase associated to hypertension

The Chromosomal High-Affinity Binding Sites for the Drosophila Dosage Compensation Complex

Dosage compensation in male Drosophila relies on the X chromosome–specific recruitment of a chromatin-modifying machinery, the dosage compensation complex (DCC). The principles that assure selective targeting of the DCC are unknown. According to a prevalent model, X chromosome targeting is initiated by recruitment of the DCC core components, MSL1 and MSL2, to a limited number of so-called “high-affinity sites” (HAS). Only very few such sites are known at the DNA sequence level, which has precluded the definition of DCC targeting principles. Combining RNA interference against DCC subunits, limited crosslinking, and chromatin immunoprecipitation coupled to probing high-resolution DNA microarrays, we identified a set of 131 HAS for MSL1 and MSL2 and confirmed their properties by various means. The HAS sites are distributed all over the X chromosome and are functionally important, since the extent of dosage compensation of a given gene and its proximity to a HAS are positively correlated. The sites are mainly located on non-coding parts of genes and predominantly map to regions that are devoid of nucleosomes. In contrast, the bulk of DCC binding is in coding regions and is marked by histone H3K36 methylation. Within the HAS, repetitive DNA sequences mainly based on GA and CA dinucleotides are enriched. Interestingly, DCC subcomplexes bind a small number of autosomal locations with similar features

Les troubles obsessionnels compulsifs et leur prise en charge (quel rôle pour le pharmacien d'officine ?)

Les troubles obsessionnels compulsifs touchent environ 2% de la population générale. Les obsessions sont une source d'anxiété, elles entraînent le sujet atteint à ritualiser, à réaliser des compulsions. Les TOC ont un fort retentissement sur la vie familiale, sociale ou professionnelle des malades. Le traitement des TOC repose essentiellement sur les antidépresseurs inhibiteurs sélectifs de la recapture de la sérotonine ainsi que sur les thérapies comportementales et cognitives. Tous les patients ne sont cependant pas répondeurs aux traitements classiques. Ainsi, pour ces TOC dits résistants, des techniques chirurgicales ainsi que des techniques de stimulation sont aujourd'hui à l'étude. Le rôle du pharmacien d'officine, outre la délivrance des médicaments, est aussi de s'assurer de la bonne compréhension du traitement et ainsi de sa bonne observance.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Tolérance et efficacité du natalizumab (suivi de 24 patients atteints de sclérose en plaques au CHU de Nantes)

La sclérose en plaques est l'affection neurologique chronique évolutive la plus fréquente chez les adultes jeunes. En 2008, on estime qu en France, 60 000 à 80 000 personnes sont atteintes de cette maladie. Son étiologie n est toujours pas connue avec précision et aujourd hui, on estime qu elle est multifactorielle. Les traitements utilisés pour l instant permettent un ralentissement de l'évolution de la pathologie, sans guérison. Le natalizumab (Tysabri®) fait partie de ces traitements. C est un anticorps monoclonal humanisé qui a obtenu l'autorisation de mise sur le marché européenne en juin 2006 et est disponible depuis avril 2007 en France, uniquement en milieu hospitalier. Il est indiqué dans les formes très actives de scléroses en plaques rémittentes-récurrentes. Il nécessite un suivi biologique et clinique strict du fait d effets indésirables potentiels graves. L étude réalisée ici sur 24 patients sous natalizumab au CHU de Nantes s'intéresse au respect des critères d'inclusion avant d'évaluer l'efficacité et la tolérance de ce traitement.NANTES-BU Médecine pharmacie (441092101) / SudocSudocFranceF

Architecture nucléaire de la séquence Fab-7 de réponse aux protéines du groupe polycomb chez la drosophile

MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

The dosage compensation complex shapes the conformation of the X chromosome in Drosophila

The dosage compensation complex (DCC) in Drosophila globally increases transcription from the X chromosome in males to compensate for its monosomy. We discovered a male-specific conformation of the X chromosome that depends on the associations of high-affinity binding sites (HAS) of the DCC. The core DCC subunits MSL1–MSL2 are responsible for this male-specific organization. Contrary to emerging concepts, we found that neither DCC assembly nor the conformation of the male X chromosome are influenced by nuclear pore components. We propose that nuclear organization of HAS is central to the faithful distribution of the DCC along the X chromosome

Inheritance of Polycomb-dependent chromosomal interactions in Drosophila

Maintenance of cell identity is a complex task that involves multiple layers of regulation, acting at all levels of chromatin packaging, from nucleosomes to folding of chromosomal domains in the cell nucleus. Polycomb-group (PcG) and trithorax-group (trxG) proteins maintain memory of chromatin states through binding at cis-regulatory elements named PcG response elements or cellular memory modules. Fab-7 is a well-defined cellular memory module involved in regulation of the homeotic gene Abdominal-B (Abd-B). In addition to its action in cis, we show here by three-dimensional FISH that the Fab-7 element leads to association of transgenes with each other or with the endogenous Fab-7, even when inserted in different chromosomes. These long-distance interactions enhance PcG-mediated silencing. They depend on PcG proteins, on DNA sequence homology, and on developmental progression. Once long-distance pairing is abolished by removal of the endogenous Fab-7, the derepressed chromatin state induced at the transgene locus can be transmitted through meiosis into a large fraction of the progeny, even after reintroduction of the endogenous Fab-7. Strikingly, meiotic inheritance of the derepressed state involves loss of pairing between endogenous and transgenic Fab-7. This suggests that transmission of nuclear architecture through cell division might contribute to inheritance of chromatin states in eukaryotes

Cell-cycle regulation of non-enzymatic functions of the Drosophila methyltransferase PR-Set7

International audienceTight cell-cycle regulation of the histone H4-K20 methyltransferase PR-Set7 is essential for the maintenance of genome integrity. In mammals, this mainly involves the interaction of PR-Set7 with the replication factor PCNA, which triggers the degradation of the enzyme by the CRL4CDT2 E3 ubiquitin ligase. PR-Set7 is also targeted by the SCFβ-TRCP ligase, but the role of this additional regulatory pathway remains unclear. Here, we show that Drosophila PR-Set7 undergoes a cell-cycle proteolytic regulation, independently of its interaction with PCNA. Instead, Slimb, the ortholog of β-TRCP, is specifically required for the degradation of the nuclear pool of PR-Set7 prior to S phase. Consequently, inactivation of Slimb leads to nuclear accumulation of PR-Set7, which triggers aberrant chromatin compaction and G1/S arrest. Strikingly, these phenotypes result from non-enzymatic PR-Set7 functions that prevent proper histone H4 acetylation independently of H4K20 methylation. Altogether, these results identify the Slimb-mediated PR-Set7 proteolysis as a new critical regulatory mechanism required for proper interphase chromatin organization at G1/S transition

Copper-catalyzed olefinic C–H difluoroacetylation of enamides

International audienc