51 research outputs found
Le gĂšne hairless de la souris : Fonctions Ă la racine du poil et au coeur dâune subtile plĂ©iotropie
Le gĂšne hairless (hr) des mammifĂšres code pour une protĂ©ine nuclĂ©aire impliquĂ©e dans le contrĂŽle du renouvellement du follicule pileux. Cette protĂ©ine est un cofacteur de rĂ©cepteurs nuclĂ©aires dâhormones qui rĂ©gulent la transcription de gĂšnes cibles au cours de la diffĂ©rentiation de lâĂ©piderme et du cycle du poil. La protĂ©ine Hairless (HR) fait partie de grands complexes multiprotĂ©iques capables de rĂ©primer la transcription, en association avec des facteurs de remodelage de la chromatine comme les histones dĂ©sacĂ©tylases. Chez les mammifĂšres, le locus hairless est la cible de nombreuses mutations allĂ©liques dont les effets sont plĂ©iotropiques. Ces altĂ©rations entraĂźnent lâapparition dâun phĂ©notype cutanĂ© complexe, caractĂ©risĂ© par la perte progressive et irrĂ©versible dâun pelage dâapparence normale au cours des premiĂšres semaines de vie post-natale. Lâanalyse de la littĂ©rature sur le gĂšne hairless chez la souris et chez lâhomme permet dâattribuer des diffĂ©rences morphologiques spĂ©cifiques Ă chaque mutant, aussi bien au niveau de lâĂ©piderme et du follicule pileux que dans dâautres tissus oĂč le gĂšne est exprimĂ© au cours du dĂ©veloppement. Ces rĂ©sultats suggĂšrent que lâintĂ©gritĂ© du gĂšne hairless est requise pour le dĂ©roulement correct de la morphogenĂšse dâorganes aussi diffĂ©rents que lâĂ©piderme, lâoreille interne, lâovaire ou le thymus. Le gĂšne hairless semble ainsi faire partie de circuits et de cascades dâinteractions gĂ©niques dont le contrĂŽle molĂ©culaire est fondamentalement inconnu. La variĂ©tĂ© des phĂ©notypes allĂ©liques souligne lâimportance de lâanalyse molĂ©culaire du locus hairless pour identifier les altĂ©rations gĂ©niques impliquĂ©es dans les diffĂ©rentes mutations dĂ©tectĂ©es. Les recherches concernant la mutation hairless ont Ă©tĂ© particuliĂšrement dynamiques pendant les derniĂšres annĂ©es, depuis que lâhomologue de ce gĂšne a pu ĂȘtre mis en Ă©vidence chez lâhomme. Cependant, un bon nombre de questions reste en suspens, notamment quant au site exact dâactivitĂ© du gĂšne hairless au sein des nombreuses populations cellulaires du follicule pileux, son rĂŽle prĂ©cis au cours de la morphogenĂšse, sa localisation au sein des voies de signalisation, ainsi que lâidentitĂ© des partenaires et des cibles de la protĂ©ine Hairless.The hairless gene in mammals encodes a nuclear factor that is highly expressed in skin and appears to control hair follicle integrity and cycling. In the absence of a normal and functional Hairless (Hr) protein, the hair bulb undergoes premature apoptosis during the first catagen stage of the hair cycle. The most striking effects of the mutation are loss of hair follicles and formation of epidermal utricles and dermal cysts. The hairless gene expression appears to be widespread and temporally regulated. The gene is strongly expressed in different compartments of the brain. Hairless mRNAs were detected in cartilage, gonads, thymus and colon. In addition to alopecia, hairless mice strains show subtle defects in the development and differentiation of various tissues and organs. The Hr protein is localised in cell nuclei and functions as a transcriptional regulator. Although its role has not been resolved in molecular terms, it was demonstrated that Hr is able to interact with multiple nuclear hormone receptors. Hr seems to be a part of a large multiprotein complex capable to repress transcription by its association to chromatin remodelling factors such as histone deacetylases. Recent experimental data suggest that Hr might be involved in Hox gene regulation, cell adhesion modulation and progenitor cells identity. At least in the skin, but probably in other organs, the Hr repressor seems to be responsible for the timing of epithelial cells differentiation
The Proteins PDIP3 and ZC11A Associate with the Human TREX Complex in an ATP-Dependent Manner and Function in mRNA Export
The conserved TREX complex, which contains UAP56, Aly, CIP29, and the multi-subunit THO complex, functions in mRNA export. Recently, several putative new components of the human TREX complex were identified by mass spectrometry. Here, we investigated the function of two of these, PDIP3 and ZC11A. Our data indicate that both of these proteins are components of a common TREX complex and function in mRNA export. Recently, we found that both CIP29 and Aly associate with the DEAD box helicase UAP56 and with the TREX complex in an ATP-dependent manner. We now show that this is also the case for PDIP3 and ZC11A. Thus, together with previous work, our data indicate that the TREX complex participates in multiple ATP-dependent interactions
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TREX exposes the RNA binding domain of Nxf1 to enable mRNA export
The metazoan TREX complex is recruited to mRNA during nuclear RNA processing and functions in exporting mRNA to the cytoplasm. Nxf1 is an mRNA export receptor, which binds processed mRNA and transports it through the nuclear pore complex. At present, the relationship between TREX and Nxf1 is not understood. Here we show that Nxf1 uses an intramolecular interaction to inhibit its own RNA binding activity. When the TREX subunits Aly and Thoc5 make contact with Nxf1, Nxf1 is driven into an open conformation, exposing its RNA binding domain, allowing RNA binding. Moreover, the combined knockdown of Aly and Thoc5 drastically reduces the amount of Nxf1 bound to mRNA in vivo and also causes a severe mRNA export block. Together, our data indicate that TREX provides a license for mRNA export by driving Nxf1 into a conformation capable of binding mRNA
Ultra-precise Masses and Magnitudes for the Gliese 268 M-dwarf Binary
Recent advances in astrometry using interferometry and precision radial velocity techniques combined allow for a significant improvement in the precision of masses of Mâdwarf stars in visual systems. We report recent astrometric observations of Gliese 268, an Mâdwarf binary with a 10.4 day orbital period, with the IOTA interferometer and radial velocity observations with the ELODIE instrument. Combining these measurements leads to preliminary masses of the constituent stars with uncertainties of 0.4%. The masses of the components are 0.22596±0.00084âM_â for the primary and 0.19230±0.00071âM_â for the secondary. The system parallax is determined by these observations to be 0.1560±.0030âarcsec (2.0% uncertainty) and is within Hipparcos error bars (0.1572±.0033). We tested these physical parameters, along with the nearâinfrared luminosities of the stars, against stellar evolution models for lowâmass stars. Discrepancies between the measured and theoretical values point toward a lowâlevel departure from the predictions. These results are among the most precise masses measured for visual binaries
Reducing the Clinical and Public Health Burden of Familial Hypercholesterolemia A Global Call to Action
Q1Q1ArtĂculo completoE1-E13IMPORTANCE Familial hypercholesterolemia (FH) is an underdiagnosed and undertreated
genetic disorder that leads to premature morbidity and mortality due to atherosclerotic
cardiovascular disease. Familial hypercholesterolemia affects 1 in 200 to 250 people around
the world of every race and ethnicity. The lack of general awareness of FH among the public
and medical community has resulted in only 10% of the FH population being diagnosed and
adequately treated. The World Health Organization recognized FH as a public health priority
in 1998 during a consultation meeting in Geneva, Switzerland. The World Health Organization
report highlighted 11 recommendations to address FH worldwide, from diagnosis and
treatment to family screening and education. Research since the 1998 report has increased
understanding and awareness of FH, particularly in specialty areas, such as cardiology and
lipidology. However, in the past 20 years, there has been little progress in implementing the
11 recommendations to prevent premature atherosclerotic cardiovascular disease in an entire
generation of families with FH.
OBSERVATIONS In 2018, the Familial Hypercholesterolemia Foundation and the World Heart
Federation convened the international FH community to update the 11 recommendations.
Two meetings were held: one at the 2018 FH Foundation Global Summit and the other during
the 2018 World Congress of Cardiology and Cardiovascular Health. Each meeting served as
a platform for the FH community to examine the original recommendations, assess the gaps,
and provide commentary on the revised recommendations. The Global Call to Action on
Familial Hypercholesterolemia thus represents individuals with FH, advocacy leaders,
scientific experts, policy makers, and the original authors of the 1998 World Health
Organization report. Attendees from 40 countries brought perspectives on FH from low-,
middle-, and high-income regions. Tables listing country-specific government support for
FH care, existing country-specific and international FH scientific statements and guidelines,
country-specific and international FH registries, and known FH advocacy organizations
around the world were created.
CONCLUSIONS AND RELEVANCE By adopting the 9 updated public policy recommendations
created for this document, covering awareness; advocacy; screening, testing, and diagnosis;
treatment; family-based care; registries; research; and cost and value, individual countries
have the opportunity to prevent atherosclerotic heart disease in their citizens carrying a gene
associated with FH and, likely, all those with severe hypercholesterolemia as well
Analyse de la régulation du gÚne Hairless et identification des voies de signalisation affectées chez les mutants «bald Mill Hill».
In Mammals, the gene hairless (Hr) encodes a nuclear factor strongly expressed in skin and crucial in controlling hair follicle integrity and cycling. In the absence of a normal and functional Hairless protein, the hair bulb undergoes premature apoptosis linked to complete and irreversible loss of hair follicles. The hairless phenotype is caused by defective proliferation and migration of the hair follicle stem cells, apparently unable to respond to various signalling molecules. The HR protein is localised in cell nuclei, tightly bound to nuclear matrix and functions as a corepressor for nuclear hormone receptors by its association to chromatin remodelling factors. At least in the skin, but probably in other organs, the HR repressor seems to be responsible for the timing of epithelial cells differentiation and tegument stem cells identity. The spatial and temporal Hr gene regulation is still poorly understood and the partners of HR protein await to be identified. The main objectives of the thesis were therefore to shed more light on the molecular basis underlying Hr gene function as well as on the HR protein implication in signalling pathways responsible for skin and hair follicle homeostasis. The first part of this thesis is thus focused on the fine mapping of cis-elements governing Hr gene basal promoter function and regulation. The precise transcriptional initiation start site of the mouse Hr gene was determined and a new 1,1 kb cis-control element (RE1) able to drive reporter expression in skin and brain derived cell lines was identified. A deletion analysis and functional exploration have shown that the role of this upstream region is linked to the presence of TR and VDR binding sites. In addition, a novel cis-regulatory motif UE60, likely to interact with both TRE and VDRE was defined. Taken together these findings reveal a complex molecular network that potentially links several signalling pathways in hair follicle formation and stress the importance of the organisation of the regulatory modules at the Hr locus in Mammals. A substantial part of the thesis work is dedicated to unravelling the signalling pathways where the Hr gene and the HR protein play a crucial role to control the hair cycle itself. A recently described mouse mutation-hairless rhino bald Mill Hill, (Hrrhbmh), was used here as a model system to approach interactions with the vitamin D signalling. It was demonstrated that the mutant HR bmh protein, although abnormally localised in the cytoplasm, is able to interact with the vitamin D receptor, but is not able to repress VDR-mediated transactivation. Immunofluorescence analysis revealed that HRbmh protein displays an abnormal cellular localization in transfected cell lines, as well as in the epidermis and hair follicle of bmh mutant mice. Finally, the patterns of HRbmh protein extra-nuclear localization were analysed in cell transfection experiments. It was established that HR bmh co-localizes specifically with the protein HDAC6, in the cytoplasm and is able to physically interact with it. The association of HR bmh with this Ub-binding protein as well as its localisation in late endosomes and lysosomes suggest that endosomal processing and/or proteasome related pathways might be able to shape and modulate the specific skin phenotype of bmh mouse hairless mutants.Le geÌne hairless (Hr) des MammifeÌres code pour un facteur nucleÌaire qui est fortement exprimeÌ dans la peau et qui semble participer au cycle de renouvellement du follicule pileux. En lâabsence de la proteÌine Hairless (HR) normale et fonctionnelle, le bulbe du poil subit une apoptose preÌcoce lieÌe aÌ la perte totale et irreÌversible de pelage. Le pheÌnotype hairless serait donc associeÌ aÌ une prolifeÌration deÌfectueuse des cellules souches du follicule pileux et leur incapaciteÌ aÌ migrer et reÌpondre aux multiples signalisations qui reÌgissent leur destineÌe. La proteÌine HR est localiseÌe dans le noyau, eÌtroitement lieÌe aÌ la matrice nucleÌaire et par son association aux facteurs de remodelage de la chromatine, fonctionne comme un coreÌpresseur de reÌcepteurs nucleÌaires dâhormones. Dans la peau, mais probablement dans dâautres organes, le reÌpresseur HR est responsable de la dynamique dans la diffeÌrenciation des cellules de la couche basale de lâeÌpiderme et de lâidentiteÌ des cellules souches du teÌgument. A lâheure actuelle, la reÌgulation de lâexpression geÌne Hr dans lâespace et dans le temps nâest pas eÌlucideÌe et les partenaires de la proteÌine HR restent eÌlusifs. Les objectifs majeurs de cette theÌse eÌtaient de mieux comprendre aussi bien les bases moleÌculaires de la reÌgulation du geÌne Hr que la façon dont la proteÌine HR serait impliqueÌe dans les grandes voies de signalisation qui gouvernent lâhomeÌostasie de la peau et du follicule pileux. La premieÌre partie de cette theÌse est ainsi centreÌe sur lâidentification des eÌleÌments en cis qui gouvernent la reÌgulation et la fonction du promoteur basal du geÌne Hr de la souris. Le site preÌcis dâinitiation de la transcription a eÌteÌ deÌtermineÌ et un nouvel eÌleÌment en cis de 1,1 kb (RE1) capable dâactiver la transcription dans des ligneÌes cellulaires dâorigine neurale et cutaneÌe, a eÌteÌ identifieÌ. GraÌce aÌ une analyse par deÌleÌtion et exploration fonctionnelle, il a eÌteÌ montreÌ que le roÌle de ce fragment est lieÌ aÌ la preÌsence de sites de fixation de TR (TRE) et VDR (VDRE). De plus, un nouveau motif reÌgulateur de 60 pb (UE60), capable dâinteragir avec TRE et VDRE a eÌteÌ deÌfini. Ces donneÌes suggeÌrent lâexistence dâun reÌseau moleÌculaire complexe qui pourrait lier plusieurs voies de signalisation, responsables de la formation du follicule pileux et mettent en relief lâimportance de lâorganisation des modules reÌgulateurs au niveau du locus hairless des MammifeÌres. Une grande partie du travail de theÌse aeÌteÌ consacreÌe au deÌcryptage des voies de signalisation qui impliquent la proteÌine HR dans le controÌle du cycle pilaire. La ligneÌe de souris mutantes bald Mill Hill (bmh), reÌcemment deÌcrite a eÌteÌ utiliseÌ comme modeÌle pour aborder la signalisation par la vitamine D. Il a eÌteÌ montreÌ que la proteÌine mutante HR bmh, localiseÌe de façon aberrante dans le cytoplasme, pouvait interagir avec VDR, mais eÌtait incapable de reÌprimer lâactivation de la transcription assureÌe par lâintermeÌdiaire de VDR. Des analyses par immunofluorescence ont eÌgalement montreÌ que la proteÌine HR bmh preÌsentait une localisation cytoplasmique anormale pas seulement en transfection transitoire, mais aussi dans lâeÌpiderme et le follicule pileux des souris mutantes bmh. Enfin, les profils de localisation extra-nucleÌaire de la proteÌine HR bmh ont eÌteÌ abordeÌs. Il a eÌteÌ eÌtabli que dans le cytoplasme HR bmh co-localise speÌcifiquement avec HDAC6 et est capable, de se lier physiquement aÌ cette proteÌine. Lâassociation de HR bmh avec une composante des complexes aÌ ubiquitine, ainsi que sa localisation dans des endosomes tardifs et des lysosmes suggeÌrent que la voie endosomale et la deÌgradation proteÌique par le proteÌasome pourraient moduler le pheÌnotype cutaneÌ du mutant bmh
Analyse de la régulation du gÚne hairless et identification des voies de signalisation affectées chez les mutants Bald Mill Hill
Le gÚne hairless (Hr) des MammifÚres code pour un facteur nucléaire qui est fortement exprimé dans la peau et qui semble contrÎler le cycle de renouvellement du follicule pileux. En l'absence de la protéine Hairless (HR) normale et fonctionnelle, le bulbe du poil subit une apoptose précoce liée à la perte totale et irréversible de pelage. Le phénotype hairless serait donc associé à une prolifération défectueuse des cellules souches dl follicule pileux et leur incapacité à migrer et répondre aux multiples signalisations qui régissent leur destinée. La protéine HR est localisée dans le noyau, étroitement liée à la matrice nucléaire et par son association aux facteurs de remodelage de la chromatine, fonctionne comme un corépresseur de récepteurs nucléaires d'hormones. Dans la peau, mais probablement dans d'autres organes, le répresseur HR est responsable de la dynamique dans la différenciation des cellules de la couche basale de l'épiderme et de l'identité des cellules souches du tégument. A l'heure actuelle, la régulation de l'expression gÚne Hr dans l'espace et dans le temps n'est pas élucidée et les partenaires de la protéine HR restent élusifs. Les objectifs majeurs de cette thÚse étaient de mieux comprendre aussi bien les bases moléculaires de la régulation du gÚne Hr que la façon dont la protéine HR serait impliquée dans les grandes voies de signalisation qui gouvernent l'homéostasie de la peau et du follicule pileux. La premiÚre partie de cette thÚse est ainsi centrée sur l'identification des éléments en cis qui gouvernent la régulation et la fonction du promoteur basal du gÚne Hr de la souris. Le site précis d'initiation de la transcription a été déterminé et un nouvel élément en cis de 1,1 kl (RE1) capable d'activer la transcription dans des lignées cellulaires d'origine neurale et cutanée, a été identifié. Grùce à une analyse par délétion et exploration fonctionnelle, il a été montré que le rÎle de ce fragment est lié à la présence de sites de fixation de TR (TRE) et VDR (VDRE). De plus, un nouveau motif régulateur de 60 pb (UE60), capable d'interagir avec TRE et VDRE a été défini. Ces données suggÚrent l'existence d'un réseau moléculaire complexe qui pourrait lier plusieurs voies de signalisation, responsables de la formation du follicule pileux et mettent en relief l'importance de l'organisation des modules régulateurs au niveau du locus hairless des MammifÚres. Une grande partie du travail de thÚse aété consacrée au décryptage des voies de signalisation qui impliquent la protéine HR dans le contrÎle du cycle pilaire. La lignéE de souris mutantes bald Mill Hill (bmh), récemment décrite a été utilisé comme modÚle pour aborder la signalisation par la vitamine D. Il a été montré que la protéine mutante HR bmh, localisée de façon aberrante dans le cytoplasme, pouvait interagir avec VDR, mais était incapable de réprimer l'activation de la transcription assurée par l'intermédiaire de VDR. Des analyses par immunofluorescence ont également montré que la protéine HR bmh présentait une localisation cytoplasmique anormale pas seulement en transfection transitoire, mais aussi dans l'épiderme et le follicule pileux des souris mutantes bmh. Enfin, les profils de localisation extra-nucléaire de la protéine HR bmh ont été abordés. Il a été établi que dans le cytoplasme HR bmh co-localise spécifiquement avec HDAC6 et est capable, de se lier physiquement à cette protéine. L'association de HR bmh avec une composante des complexes à ubiquitine, ainsi que sa localisation dans des endosomes tardifs et des Iysosmes suggÚrent que la voie endosomale et la dégradation protéique par le protéasome pourraient moduler le phénotype cutané du mutant bmh.ln Mammals, the gene hairless (Hr) encodes a nuclear factor strongly expressed in skin and crucial in controlling hair follicle integrity and cycling. ln the absence of a normal and functional Hairless protein, the hai bulb undergoes premature apoptosis linked to complete and irreversible loss of hair follicles. The hairless phenotype is caused by defective proliferation and migration of the hair follicle stem cells, apparently unable t, respond to various signalling molecules. The HR protein is localised in cell nuclei, tightly bound to nuclear matrix and functions as a corepressor for nuclear hormone receptors by its association to chromatin remodelling factors. At least in the skin, but probably in other organs, the HR repressor seems to be responsible for the timing of epithelial cells differentiation and tegument stem cells identity. The spatial and temporal Hr gene regulation is still poorly understood and the partners of HR protein await to be identified. Th, main objectives of the thesis were therefore to shed more light on the molecular basis underlying Hr gene function as weil as on the HR protein implication in signalling pathways responsible for skin and hair follicle homeostasis. The first part of this thesis is thus focused on the fine mapping of cis-elements governing Hr gene basal promoter function and regulation. The precise transcriptional initiation start site of the mouse Hr gene was determined and a new 1,1 kb cis-control element (RE1) able to drive reporter expression in skin an brain derived celllines was identified. A deletion analysis and functional exploration have shown that the role of this upstream region is linked to the presence of TR and VDR binding sites. ln addition, a novel cis reaulatorv motif UE60, likelv to interact with both TRE and VDRE was defined. Taken together these findings reveal a complex molecular network that potentially links several signalling pathways in hair follicle formation and stress the importance of the organisation of the regulatory modules at the Hr locus in Mammals. A substantial part of the thesis work is dedicated to unravelling the signalling pathways where the Hr gene and the HR protein play a crucial role to control the hair cycle itself. A recently described mouse mutation-hairless rhino bald Mill Hill, (H('1bmh), was used here as a model system to approach interactions with the vitamin 0 signalling. It was demonstrated that the mutant HR bmh protein, although abnormally localised in the cytoplasm, is able to interact with the vitamin 0 receptor, but is not able to repress VDR-mediated transactivation. Immunofluorescence analysis revealed that HRbmh protein displays an abnormal cellular localization in transfected ceillines, as weil as in the epidermis and hair follicle of bmh mutant mice. Finally, the patterns of HRbmh protein extra-nuclear localization were analysed in cell transfection experiments. It wa established that HR bmh co-Iocalizes specifically with the protein HDAC6, in the cytoplasm and is able to physically interact with il. The association of HR bmh with this Ub-binding protein as weil as its localisation in late endosomes and lysosomes suggest that endosomal processing and/or proteasome related pathways miaht be able to shaoe and modulate the soecific skin ohenotvoe of bmh mouse hairless mutants.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF
The anti-tumor drug E7107 reveals an essential role for SF3b in remodeling U2 snRNP to expose the branch point-binding region
Duplex formation between the branch point-binding region (BBR) of U2 snRNA and the branch point sequence (BPS) in the intron is essential for splicing. Both the BBR and BPS interact with the U2 small nuclear ribonucleoprotein (snRNP)-associated SF3b complex, which is the target of the anti-tumor drug E7107. We show that E7107 blocks spliceosome assembly by preventing tight binding of U2 snRNP to pre-mRNA. E7107 has no apparent effect on U2 snRNP integrity. Instead, E7107 abolishes an ATP-dependent conformational change in U2 snRNP that exposes the BBR. We conclude that SF3b is required for this remodeling, which exposes the BBR for tight U2 snRNP binding to pre-mRNA
[The mouse hairless gene: its function in hair root and at the heart of a subtle pleiotropy]
International audienceThe hairless gene in mammals encodes a nuclear factor that is highly expressed in skin and appears to control hair follicle integrity and cycling. In the absence of a normal and functional Hairless (Hr) protein, the hair bulb undergoes premature apoptosis during the first catagen stage of the hair cycle. The most striking effects of the mutation are loss of hair follicles and formation of epidermal utricles and dermal cysts. The hairless gene expression appears to be widespread and temporally regulated. The gene is strongly expressed in different compartments of the brain. Hairless mRNAs were detected in cartilage, gonads, thymus and colon. In addition to alopecia, hairless mice strains show subtle defects in the development and differentiation of various tissues and organs. The Hr protein is localised in cell nuclei and functions as a transcriptional regulator. Although its role has not been resolved in molecular terms, it was demonstrated that Hr is able to interact with multiple nuclear hormone receptors. Hr seems to be a part of a large multiprotein complex capable to repress transcription by its association to chromatin remodelling factors such as histone deacetylases. Recent experimental data suggest that Hr might be involved in Hox gene regulation, cell adhesion modulation and progenitor cells identity. At least in the skin, but probably in other organs, the Hr repressor seems to be responsible for the timing of epithelial cells differentiation
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