38 research outputs found
Un dimanche à Robinson / Bruno LORENZONI et son Ensemble musette
No full textTitre uniforme : [Retour des hirondelles]Titre uniforme : [Istambul]Titre uniforme : [Le retour des hirondelles]Titre uniforme : [Coplas]Comprend : Rose-Marie polka / M. HARDEN - Régal musette / R. TRABUCCO - ISTAMBUL / N. SIMON - Amicalement / B. LORENZANI - Visite au musette / A. HUARD junior - Polka des moucherons / J. PERRONIN - Le chalet s'éveille / JARO - Je te Lele / JOSE et ANA - Fete de l'accordéon / LORENZONI et HUARD - NENETTE / W. LECOINTE - Retour des hirondelles / TROGNEE et PAGANO - Dis la vérité / L. ARAGNE et J. BERARD - L'espiègle / R. RENAUD - PRINTEMPS D'ALSACE / L. LEDRICH - COPLAS / MOSTAZOBnF-Partenariats, Collection sonore - BelieveContient une table des matière
A Saint Charles et à Saint Simon. Recueil de pensées et d'hommages dédiés à l'amitié
No full textAvec mode text
Non-syndromic Mitral Valve Dysplasia Mutation Changes the Force Resilience and Interaction of Human Filamin A
No full textInternational audienceFilamin A (FLNa), expressed in endocardial endothelia during fetal valve morphogenesis, is key in cardiac development. Missense mutations in FLNa cause non-syndromic mitral valve dysplasia (FLNA-MVD). Here, we aimed to reveal the currently unknown underlying molecular mechanism behind FLNA-MVD caused by the FLNa P637Q mutation. The solved crystal structure of the FLNa3-5 P637Q revealed that this mutation causes only minor structural changes close to mutation site. These changes were observed to significantly affect FLNa's ability to transmit cellular force and to interact with its binding partner. The performed steered molecular dynamics simulations showed that significantly lower forces are needed to split domains 4 and 5 in FLNA-MVD than with wild-type FLNa. The P637Q mutation was also observed to interfere with FLNa's interactions with the protein tyrosine phosphatase PTPN12. Our results provide a crucial step toward understanding the molecular bases behind FLNA-MVD, which is critical for the development of drug-based therapeutics
Cellular location and activity of Escherichia coli RecG proteins shed light on the function of its structurally unresolved C-terminus
No full textRecG is a DNA translocase encoded by most species of bacteria. The Escherichia coli protein targets branched DNA substrates and drives the unwinding and rewinding of DNA strands. Its ability to remodel replication forks and to genetically interact with PriA protein have led to the idea that it plays an important role in securing faithful genome duplication. Here we report that RecG co-localises with sites of DNA replication and identify conserved arginine and tryptophan residues near its C-terminus that are needed for this localisation. We establish that the extreme C-terminus, which is not resolved in the crystal structure, is vital for DNA unwinding but not for DNA binding. Substituting an alanine for a highly conserved tyrosine near the very end results in a substantial reduction in the ability to unwind replication fork and Holliday junction structures but has no effect on substrate affinity. Deleting or substituting the terminal alanine causes an even greater reduction in unwinding activity, which is somewhat surprising as this residue is not uniformly present in closely related RecG proteins. More significantly, the extreme C-terminal mutations have little effect on localisation. Mutations that do prevent localisation result in only a slight reduction in the capacity for DNA repair. © 2014 The Author(s)
Filamin-A-Related Myxomatous Mitral Valve Dystrophy: Genetic, Echocardiographic and Functional Aspects
No full text0493: Mutations in the gene encoding FilGAP as a cause for mitral valve prolapse
No full textThe mitral valve prolapse (MVP) is a common cardiac disorder which affects 2-4% of the population and remains one of the most frequent indications for valvular surgery. The familial nature of MVP has been proposed for many years and so far, FLNA remains the only identified gene.Recently, it has been shown that FLNA mutations deregulate the RhoA/ Rac1 GTPases balance and provided evidences for a role of the Rac1 specific GTPase activating protein, FilGAP, in this network. FilGAP is a recognized FlnA-binding RhoGTPase-activating protein.Giving the tight interactions of FlnA and FilGAP, we first tested, using a candidate gene approach, the hypothesis that FilGAP, encoded by ARHGAP24, could be involved in MVP.We have sequenced ARHGAP24 in 95 MVP operated patients and identified 3 rare missense mutations in highly conserve residues (FilGAP p.R95Q; p.P417H and p.T481M). One mutation was novel and the 2 others present a minor allele frequency lower than 0.1% in EVS. Moreover, p.T481M co-segregates with the pathology in a family with 3 affected patients.We then investigated the impact of these mutations in HEK293 cells. The role of FilGAP is to decrease Rac1 activity and thus to regulate cell processes involved in actin cytoskeleton properties as adhesion, protrusion and intracellular dynamics.From pull-down assays, we have shown that FilGAP mutations alter Rac1 GTPase activity and significantly decrease the FilGAP interaction with the active form of Rac1 (p<0.01). We have also shown, using the XCELLigence system, that cell adhesion and spreading was significantly increased with mutated FilGAP (p<0.01). Our results indicate that ARHGAP24 variants are loss-function mutations.Moreover, we demonstrate that FilGAP mutations alter the downstream signaling pathway by two different mechanisms. FilGAP p.P417H and p.T481M decrease the interaction with FlnA while p.R95Q impacts the plasma membrane anchorage.This work reinforces the involvement of GTPases pathway in MVP pathogenesis
Critical Structural Defects Explain Filamin A Mutations Causing Mitral Valve Dysplasia
No full textMitral valve diseases affect approximately 3% of the population and are the most common reasons for valvular surgery because no drug-based treatments exist. Inheritable genetic mutations have now been established as the cause of mitral valve insufficiency, and four different missense mutations in the filamin A gene (FLNA) have been found in patients suffering from non-syndromic mitral valve dysplasia (MVD). The FLNA protein is expressed, in particular, in endocardial endothelia during fetal valve morphogenesis and is key in cardiac development. The FLNA-MVD causing mutations are clustered in the N-terminal region of FLNA. How the mutations in FLNA modify its structure and function, have mostly remained elusive. In this study, using NMR spectroscopy and interaction assays, we investigated FLNA-MVD causing V711D and H743P mutations. Our results clearly indicated that both mutations almost completely destroy the folding of the FLNA5 domain, where the mutation is located, and also affect the folding of the neighboring FLNA4 domain. The structure of the neighboring FLNA6 domain was not affected by the mutations. These mutations also completely abolish FLNA’s interactions with protein tyrosine phosphatase (PTP) non-receptor type 12 (PTPN12), which has been suggested to contribute to the pathogenesis of FLNA-MVD. Taken together, our results provide an essential structural and molecular framework for understanding the molecular bases of FLNA-MVD, which is crucial for the development of new therapies to replace surgery.peerReviewe
0216 : Involvement of the receptor-type tyrosine-protein phosphatase F gene PTPRF, a cell adhesion-like molecule, in Mitral Valve Prolapse (MVP)
No full text0268 : Involvement of LRRFip1 gene and canonical Wnt pathway in Mitral Valve Prolapse (MVP)
No full textHeart valves diseases affect 3% of world population, and surgery is often the only therapeutic mean. A genetic study performed on a family in which several members exhibited a MVP identified a R94G mutation on LRRFip1 gene. LRRFip1 alternative transcription splicing gives rise to five isoforms in humans, three of which are targeted by the mutation (Iso1, 3 and 4). Previous studies only focused on LRRFip1-iso5 that was first described as a transcription factor interacting with positive (Dishevelled) and negative (Flightless-1) regulators of the canonical Wnt β-catenin dependant pathway. As it may participate and regulate crucial events of cardiac valve development and homeostasis involving Wnt pathway, we hypothesised that LRRFip1 could be involved in MVP pathology. We first analysed the expression of LRRFip1 in valves by RNA sequencing and quantitative PCR and showed that LRRFip1- iso1 is expressed in human valves. In mouse, it prevails during embryonic development and then levels down to that other isoforms expression. We thus focused on LRRFip-iso1. Using cell fractionation, we showed a nuclear localization of LRRFip1-iso1 while other isoforms are strictly cytoplasmic. Using luciferase-based Wnt reporter assays and co-IP, we further demonstrated that out of the five isoforms, LRRFip1-iso1 is the strongest interactor of Dvl-1 and Fli-1, and the strongest activator of the canonical Wnt pathway. Although activation requires beta-catenin, it does not involve beta-catenin stabilization nor activation. Using site directed mutagenesis, we mapped the domain responsible for Wnt pathway activation to the 25 amino-acids region surrounding arginine 94 and showed that R94G mutation also decreases Wnt activation. This work demonstrates the involvement of LRRFip1-iso1 in canonical Wnt pathway activation. Taken together, our results suggest a potential role for LRRFip1 in valvulogenesis and/or valve homeostasis regulation that may be impeded by the R94G mutation
