Mycolactone subverts immunity by selectively blocking the Sec61 translocon

Mycolactone, an immunosuppressive macrolide released by the human pathogen Mycobacterium ulcerans, was previously shown to impair Sec61-dependent protein translocation, but the underlying molecular mechanism was not identified. In this study, we show that mycolactone directly targets the alpha subunit of the Sec61 translocon to block the production of secreted and integral membrane proteins with high potency. We identify a single-amino acid mutation conferring resistance to mycolactone, which localizes its interaction site near the lumenal plug of Sec61 alpha. Quantitative proteomics reveals that during T cell activation, mycolactone-mediated Sec61 blockade affects a selective subset of secretory proteins including key signal-transmitting receptors and adhesion molecules. Expression of mutant Sec61 alpha in mycolactone-treated T cells rescued their homing potential and effector functions. Furthermore, when expressed in macrophages, the mycolactone-resistant mutant restored IFN-gamma receptor-mediated antimicrobial responses. Thus, our data provide definitive genetic evidence that Sec61 is the host receptor mediating the diverse immunomodulatory effects of mycolactone and identify Sec61 as a novel regulator of immune cell functions.Peer reviewe

Pre-microRNA and Mature microRNA in Human Mitochondria

Chantier qualité GAInternational audienceBACKGROUND: Because of the central functions of the mitochondria in providing metabolic energy and initiating apoptosis on one hand and the role that microRNA (miRNA) play in gene expression, we hypothesized that some miRNA could be present in the mitochondria for post-transcriptomic regulation by RNA interference. We intend to identify miRNA localized in the mitochondria isolated from human skeletal primary muscular cells. METHODOLOGY/PRINCIPAL FINDINGS: To investigate the potential origin of mitochondrial miRNA, we in-silico searched for microRNA candidates in the mtDNA. Twenty five human pre-miRNA and 33 miRNA aligments (E-value35) for the smallest RNA input concentration and 204 miRNA for the maximum RNA input concentration. In silico analysis predicted 80 putative miRNA target sites in the mitochondrial genome (E-value<0.05). CONCLUSIONS/SIGNIFICANCE: The present study experimentally demonstrated for the first time the presence of pre-miRNA and miRNA in the human mitochondria isolated from skeletal muscular cells. A set of miRNA were significantly detected in mitochondria fraction. The origin of these pre-miRNA and miRNA should be further investigate to determine if they are imported from the cytosol and/or if they are partially processed in the mitochondria

Control of Gene Expression by the Retinoic Acid-Related Orphan Receptor Alpha in HepG2 Human Hepatoma Cells

Retinoic acid-related Orphan Receptor alpha (RORα; NR1F1) is a widely distributed nuclear receptor involved in several (patho)physiological functions including lipid metabolism, inflammation, angiogenesis, and circadian rhythm. To better understand the role of this nuclear receptor in liver, we aimed at displaying genes controlled by RORα in liver cells by generating HepG2 human hepatoma cells stably over-expressing RORα. Genes whose expression was altered in these cells versus control cells were displayed using micro-arrays followed by qRT-PCR analysis. Expression of these genes was also altered in cells in which RORα was transiently over-expressed after adenoviral infection. A number of the genes found were involved in known pathways controlled by RORα, for instance LPA, NR1D2 and ADIPOQ in lipid metabolism, ADIPOQ and PLG in inflammation, PLG in fibrinolysis and NR1D2 and NR1D1 in circadian rhythm. This study also revealed that genes such as G6PC, involved in glucose homeostasis, and AGRP, involved in the control of body weight, are also controlled by RORα. Lastly, SPARC, involved in cell growth and adhesion, and associated with liver carcinogenesis, was up-regulated by RORα. SPARC was found to be a new putative RORα target gene since it possesses, in its promoter, a functional RORE as evidenced by EMSAs and transfection experiments. Most of the other genes that we found regulated by RORα also contained putative ROREs in their regulatory regions. Chromatin immunoprecipitation (ChIP) confirmed that the ROREs present in the SPARC, PLG, G6PC, NR1D2 and AGRP genes were occupied by RORα in HepG2 cells. Therefore these genes must now be considered as direct RORα targets. Our results open new routes on the roles of RORα in glucose metabolism and carcinogenesis within cells of hepatic origin

Total synthesis of mycolactones A/B and targeted analogues towards the mechanistic study of Buruli ulcer

L’ulcère de Buruli est une maladie nécrotique de la peau présente dans plus de trente pays dans le monde, et affectant principalement le continent africain et l’Océanie. L’infection est due à Mycobacterium ulcerans (M. ulcerans), un micro-organisme qui sécrète une exotoxine appelée mycolactone, représentant le premier polycétide isolé d’un pathogène humain. La maladie est caractérisée par la formation progressive de lésions nécrotiques combinée à une absence de réponse immunitaire et de sensation de douleur ; la mycolactone est connue pour être directement impliquée dans ce mécanisme biologique. A ce jour, aucun traitement totalement performant et spécifique contre l’ulcère de Buruli n’a été développé, ce qui révèle le manque crucial de connaissances sur les mécanismes chimique et biologique. Dans ce contexte, le projet développé s’intéresse à l’élucidation du mécanisme d’action des mycolactones en utilisant la synthèse totale comme outil principal. Pour cela, notre équipe a mis au point une voie de synthèse modulaire permettant la préparation de la toxine naturelle et de ses différents analogues en vue de les tester biologiquement et d’affiner ainsi notre compréhension mécanistique de cette infection.Buruli ulcer is a necrotizing skin disease present in more than thirty countries in the world, located mainly in West and Central Africa but also in Australia and in Japan. This infection is caused by Mycobacterium ulcerans (M. ulcerans) that secretes a macrolide toxin called mycolactone, which is the first polyketide isolated from a human pathogen. The disease is characterized by the formation of painless progressive necrotic lesions combined with a lack of acute inflammatory response, and mycolactone is known to be directly involved in the biological mechanism. To date no specific and completely efficient treatment of Buruli ulcer has been developed which correlates with the dramatic lack of understanding of the associated chemical and biological mechanisms. In this context, this research project aims at a better understanding of mycolactone A/B molecular interactions by using total synthesis as main tool. To this end, our research team has developed an efficient synthetic pathway allowing the preparation of the natural toxin and its differents analogues for purposes of their biological evaluation and fine-tuning our mechanical understanding of this infection

Total synthesis of mycolactones A/B and targeted analogues towards the mechanistic study of Buruli ulcer

L’ulcère de Buruli est une maladie nécrotique de la peau présente dans plus de trente pays dans le monde, et affectant principalement le continent africain et l’Océanie. L’infection est due à Mycobacterium ulcerans (M. ulcerans), un micro-organisme qui sécrète une exotoxine appelée mycolactone, représentant le premier polycétide isolé d’un pathogène humain. La maladie est caractérisée par la formation progressive de lésions nécrotiques combinée à une absence de réponse immunitaire et de sensation de douleur ; la mycolactone est connue pour être directement impliquée dans ce mécanisme biologique. A ce jour, aucun traitement totalement performant et spécifique contre l’ulcère de Buruli n’a été développé, ce qui révèle le manque crucial de connaissances sur les mécanismes chimique et biologique. Dans ce contexte, le projet développé s’intéresse à l’élucidation du mécanisme d’action des mycolactones en utilisant la synthèse totale comme outil principal. Pour cela, notre équipe a mis au point une voie de synthèse modulaire permettant la préparation de la toxine naturelle et de ses différents analogues en vue de les tester biologiquement et d’affiner ainsi notre compréhension mécanistique de cette infection.Buruli ulcer is a necrotizing skin disease present in more than thirty countries in the world, located mainly in West and Central Africa but also in Australia and in Japan. This infection is caused by Mycobacterium ulcerans (M. ulcerans) that secretes a macrolide toxin called mycolactone, which is the first polyketide isolated from a human pathogen. The disease is characterized by the formation of painless progressive necrotic lesions combined with a lack of acute inflammatory response, and mycolactone is known to be directly involved in the biological mechanism. To date no specific and completely efficient treatment of Buruli ulcer has been developed which correlates with the dramatic lack of understanding of the associated chemical and biological mechanisms. In this context, this research project aims at a better understanding of mycolactone A/B molecular interactions by using total synthesis as main tool. To this end, our research team has developed an efficient synthetic pathway allowing the preparation of the natural toxin and its differents analogues for purposes of their biological evaluation and fine-tuning our mechanical understanding of this infection

Synthèse totale de mycolactone A/B et d'analogues ciblés pour l'étude mécanistique de l'ulcère de Buruli

Buruli ulcer is a necrotizing skin disease present in more than thirty countries in the world, located mainly in West and Central Africa but also in Australia and in Japan. This infection is caused by Mycobacterium ulcerans (M. ulcerans) that secretes a macrolide toxin called mycolactone, which is the first polyketide isolated from a human pathogen. The disease is characterized by the formation of painless progressive necrotic lesions combined with a lack of acute inflammatory response, and mycolactone is known to be directly involved in the biological mechanism. To date no specific and completely efficient treatment of Buruli ulcer has been developed which correlates with the dramatic lack of understanding of the associated chemical and biological mechanisms. In this context, this research project aims at a better understanding of mycolactone A/B molecular interactions by using total synthesis as main tool. To this end, our research team has developed an efficient synthetic pathway allowing the preparation of the natural toxin and its differents analogues for purposes of their biological evaluation and fine-tuning our mechanical understanding of this infection.L’ulcère de Buruli est une maladie nécrotique de la peau présente dans plus de trente pays dans le monde, et affectant principalement le continent africain et l’Océanie. L’infection est due à Mycobacterium ulcerans (M. ulcerans), un micro-organisme qui sécrète une exotoxine appelée mycolactone, représentant le premier polycétide isolé d’un pathogène humain. La maladie est caractérisée par la formation progressive de lésions nécrotiques combinée à une absence de réponse immunitaire et de sensation de douleur ; la mycolactone est connue pour être directement impliquée dans ce mécanisme biologique. A ce jour, aucun traitement totalement performant et spécifique contre l’ulcère de Buruli n’a été développé, ce qui révèle le manque crucial de connaissances sur les mécanismes chimique et biologique. Dans ce contexte, le projet développé s’intéresse à l’élucidation du mécanisme d’action des mycolactones en utilisant la synthèse totale comme outil principal. Pour cela, notre équipe a mis au point une voie de synthèse modulaire permettant la préparation de la toxine naturelle et de ses différents analogues en vue de les tester biologiquement et d’affiner ainsi notre compréhension mécanistique de cette infection

The Divestiture of the company's shares between relatives

Le régime de cession des droits sociaux applicable des entre les membres d’une même famille est certes privilégié. Mais le législateur ne prend en compte que certains d’entre eux, à savoir, les ascendants, les descendants et certains collatéraux. Pourtant, les parts sociales ou actions font parties des biens patrimoniaux de la famille. Cette mise en société sert de prétexte à une meilleure gestion du patrimoine familial, mais aussi à sa cession au sein de la famille. L’objectif souvent non avoué est la pérennisation de l’entreprise familiale au sein de la famille. Toutefois, législateur ne reconnait toujours pas tous les types de schémas familiaux contemporains. Et pour cause, la notion de famille n’est pas définie en droit. Pourtant cette définition serait bien utile pour soumettre les cessions entre proches à un régime bien spécifique. La conséquence est que la pratique des affaires a développée quantité de règles pour permettre aux associés familiaux soit de rester ensemble au sein de la société ou d’en sortir. En effet, les aléas de la vie familiale commandent les cessions. Ce sont souvent des pactes extra-statutaires qui servent de support à la cession des titres. Le problème est qu’ils n’engagent que leurs signataires. Autrement dit, les associés familiaux non signataires de ces pactes ne sont pas concernés par ceux-ci. Pourtant, ils font partie de la même société et de la même famille. Peuvent-ils pour autant élever contestation en justice ? Car à bien des égards, ces pactes sont souvent à la frontière de l’illégalité notamment celle de l’interdiction des pactes sur succession future. Alors, la liberté de cession du cédant serait-elle empêchée dans le cadre d’une société familiale ? L’élément de réponse se trouve sans doute dans la consécration du pacte de famille, un nouvel outil juridique autonome destiné à compléter efficacement les statuts de la société.The system of transfer of the corporate holdings of the company applicable between members of the same family is certainly privileged. But the legislator only takes into account some of them namely, ascendants, descendants and some collaterals. However, shares or stocks are part of the family's patrimonial assets. This incorporation serves as a pretext for better management of the family patrimony, but also for its transfer within the family. The often unstated aim is the sustainability of the family business within the family. However, legislator still does not recognize all types of contemporary family patterns. And for good reason, the notion of family is not defined in law. Yet this definition would be very useful to submit the transfers between relatives to a specific regime. The consequence is that business practice has developed a lot of rules to allow family partners to either stay together in society or get out of it. Indeed, the vagaries of family life command shares disposal. These are often extra-statutory pacts that serve as a support for the sale of securities. The problem is that they only commit their signatories. In other words, non-signatory family members of these pacts are not affected by them. Yet they are part of the same company and the same family. Can they raise a challenge in court? Because in many ways, these pacts are often on the borderline of illegality, including the prohibition of pacts respecting a future succession. Could the transferor's freedom of assignment be prevented in the context of a family company? The element of response is undoubtedly in the consecration of the family pact, a new independent legal tool designed to effectively supplement the company statutes

Virtual Reality for the Preservation and Promotion of Historical Real Tennis

International audienceReal tennis or "courte paume" in its original naming in French, is a racket sport that has been played for centuries and is considered the ancestor of tennis. It was a very popular sport in Europe during the Renaissance period, practiced in every layer of the society. It is still practiced today in few courts in the world, especially in United Kingdom, France, Australia, and USA. It has been listed in the Inventory of Intangible Cultural Heritage in France since 2012. The goal of our project is to elicit interest in this historical sport and for the new and future generations to experience it. We developped a virtual environment that enables its users to experience real tennis game. This environment was then tested to assess its acceptability and usability in different context of use. We found that such use of virtual reality enabled our participants to discover the history and rules of this sport, in a didactic and pleasant manner. We hope that our VR application will encourage younger and future generations to play real tennis

Virtual Reality for the Preservation and Promotion of Historical Real Tennis

International audienceReal tennis or "courte paume" in its original naming in French, is a racket sport that has been played for centuries and is considered the ancestor of tennis. It was a very popular sport in Europe during the Renaissance period, practiced in every layer of the society. It is still practiced today in few courts in the world, especially in United Kingdom, France, Australia, and USA. It has been listed in the Inventory of Intangible Cultural Heritage in France since 2012. The goal of our project is to elicit interest in this historical sport and for the new and future generations to experience it. We developped a virtual environment that enables its users to experience real tennis game. This environment was then tested to assess its acceptability and usability in different context of use. We found that such use of virtual reality enabled our participants to discover the history and rules of this sport, in a didactic and pleasant manner. We hope that our VR application will encourage younger and future generations to play real tennis