175 research outputs found

    RNAi in mice: a promising approach to decipher gene functions in vivo

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    International audienceRNA interference (RNAi) is a simple and powerful tool widely used to study gene functions in many species. Vector-based systems using RNA polymerase III promoters have been developed to achieve stable expression of small interfering RNA (siRNA) or small hairpin RNA (shRNA) in mammalian cells. Recent investigations demonstrated that when, combined with the Cre-loxP system, the vector-based RNAi can be used to achieve conditional or tissue specific knockdown of endogenous genes with high efficiency in mice. Here, we review these recent progresses and discuss the advantages, limitations and future development of this emerging technology

    Roles of FGF Receptors in Mammalian Development and Congenital Diseases

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    International audienceFour fibroblast growth factor receptors (FGFR1-4) constitute a family of transmembrane tyrosine kinases that serve as high affinity receptors for at least 22 FGF ligands. Gene targeting in mice has yielded valuable insights into the functions of this important gene family in multiple biological processes. These include mesoderm induction and patterning; cell growth, migration, and differentiation; organ formation and maintenance; neuronal differentiation and survival; wound healing; and malignant transformation. Furthermore, discoveries that mutations in three of the four receptors result in more than a dozen human congenital diseases highlight the importance of these genes in skeletal development. In this review, we will discuss recent progress on the roles of FGF receptors in mammalian development and congenital diseases, with an emphasis on signal transduction pathways

    RNAi-based conditional gene knockdown in mice using a U6 promoter driven vector

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    RNA interference (RNAi) is a powerful tool widely used for studying gene function in a number of species. We have previously developed an approach that allows conditional expression of a polymerase III promoter based small hairpin RNA (shRNA) in mice using the Cre-LoxP system. This approach uses a U6 promoter, which is inactive due to the presence of a ploxPneo cassette in the promoter; this promoter can be activated after excision of the neo gene in transgenic mice that express a Cre recombinase transgene. As a proof of principle, we have previously knocked down over 95% of Fgfr2 transcripts in mouse germlines, leading to embryonic lethality, while restricting the knockdown to the progress zone of the limb results in live animals with malformation of digits of both the forelimbs and hindlimbs. We now provide a detailed protocol, including a simplified single-step cloning procedure for vector construction. This method provides a fast yet efficient way to decipher gene functions in vivo in a tissue specific manner

    Aryl hydrocarbon receptor-dependent upregulation of Cyp1b1 by TCDD and diesel exhaust particles in rat brain microvessels

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    <p>Abstract</p> <p>Background</p> <p>AhR activates the transcription of several target genes including CYP1B1. Recently, we showed <it>CYP1B1 </it>as the major cytochrome P450 (CYP) enzyme expressed in human brain microvessels. Here, we studied the effect of AhR activation by environmental pollutants on the expression of Cyp1b1 in rat brain microvessels.</p> <p>Methods</p> <p>Expression of AhR and Cyp1b1 was detected in isolated rat brain microvessels. AhR was immunovisualised in brain microvessel endothelial cells. The effect of AhR ligands on Cyp1b1 expression was studied using isolated brain microvessels after <it>ex vivo </it>and/or <it>in vivo </it>exposure to TCDD, heavy hydrocarbons containing diesel exhaust particles (DEP) or Δ<sup>9</sup>-tetrahydrocannabinol (Δ<sup>9</sup>-THC).</p> <p>Results</p> <p>After <it>ex vivo </it>exposure to TCDD (a highly potent AhR ligand) for 3 h, <it>Cyp1b1 </it>expression was significantly increased by 2.3-fold in brain microvessels. A single i.p. dose of TCDD also increased <it>Cyp1b1 </it>transcripts (22-fold) and Cyp1b1 protein (2-fold) in rat brain microvessels at 72 h after TCDD. Likewise, DEP treatment (<it>in vivo </it>and <it>ex vivo</it>) strongly induced Cyp1b1 protein in brain microvessels. DEP-mediated Cyp1b1 induction was inhibited by actinomycin D, cycloheximide, or by an AhR antagonist. In contrast, a sub-chronic <it>in vivo </it>treatment with Δ<sup>9</sup>-THC once daily for 7 seven days had no effect on <it>Cyp1b1 </it>expression</p> <p>Conclusions</p> <p>Our results show that TCDD and DEP strongly induced Cyp1b1 in rat brain microvessels, likely through AhR activation.</p

    Structure-based design, synthesis and characterization of the first irreversible inhibitor of Focal Adhesion Kinase

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    Focal Adhesion Kinase signaling pathway and its functions have been involved in the development and aggressiveness of tumor malignancy, it then presents a promising cancer therapeutic target. Several reversible FAK inhibitors have been developed and are being conducted in clinical trials. On the other hand, irreversible covalent inhibitors would bring many desirable pharmacological features including high potency and increased duration of action. Herein we report the structure-guided development of the first highly potent and irreversible inhibitor of the FAK kinase. This inhibitor showed a very potent decrease of autophosphorylation of FAK in squamous cell carcinoma. A cocrystal structure of the FAK kinase domain in complex with this compound revealed the inhibitor binding mode within the ATP binding site and confirmed the covalent linkage between the targeted Cys427 of the protein and the inhibitor

    Aryl hydrocarbon receptor and cysteine redox dynamics underlie (Mal)adaptive mechanisms to chronic intermittent hypoxia in kidney cortex

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    Funding Information: Funding: This work was supported by Fundação para Ciência e Tecnologia [PTDC/MED-TOX/30418/2017] and iNOVA4Health [UID/Multi/04462/2013]. M.J.C., F.L.-C., N.R.C., C.G.-D. and J.M. are supported by FCT grants [SFRH/BD/131331/2017, PD/BD/128337/2017, PD/BD/114257/2016, and PD/BD/105892/2014, PTDC/MED-TOX/30418/2017 respectively]. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.We hypothesized that an interplay between aryl hydrocarbon receptor (AhR) and cysteine-related thiolome at the kidney cortex underlies the mechanisms of (mal)adaptation to chronic intermittent hypoxia (CIH), promoting arterial hypertension (HTN). Using a rat model of CIH-HTN, we investigated the impact of short-term (1 and 7 days), mid-term (14 and 21 days, pre-HTN), and long-term intermittent hypoxia (IH) (up to 60 days, established HTN) on Cyp1a1 protein level (a sensitive hallmark of AhR activation) and cysteine-related thiol pools. We found that acute and chronic IH had opposite effects on Cyp1a1 and the thiolome. While short-term IH decreased Cyp1a1 and increased protein-S-thiolation, long-term IH increased Cyp1a1 and free oxidized cysteine. In addition, an in vitro administration of cystine, but not cysteine, to human endothelial cells increased Cyp1a1 expression, supporting cystine as a putative AhR activator. This study supports Cyp1a1 as a biomarker of obstructive sleep apnea (OSA) severity and oxidized pools of cysteine as risk indicator of OSA-HTN. This work contributes to a better understanding of the mechanisms underlying the phenotype of OSA-HTN, mimicked by this model, which is in line with precision medicine challenges in OSA.publishersversionpublishe

    Dioxine et œstradiol

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    Les effets des co-expositions du BaP avec des nanoparticules: Effets du B(a)P seul ou en co-exposition avec des nanoparticules et implication du récepteur Ah (ou AhR) dans l’intégrité et la fonction de deux barrières physiologiques : broncho-pulmonaire et placentaire

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    National audienceLa première cible du BaP, après son inhalation, est l’épithélium respiratoire mais il peut aussi franchir facilement les barrières physiologiques et atteindre d’autres organes en quelques minutes ou quelques heures via la circulation sanguine. Le placenta constitue, chez la femme enceinte, une deuxième barrière pour protéger le fœtus. Ainsi, le benzo(a)pyrène (BaP) peut être métabolisé au niveau des barrières physiologiques, en formant des métabolites réactifs, capables de former des adduits au niveau de l’ADN. Ce qui suggère qu’il pourrait altérer leurs fonctions ou avoir des actions systémiques. En effet, le BaP est un puissant ligand du récepteur des hydrocarbures aromatiques (AhR), un facteur de transcription qui régule l’expression de nombreux gènes de l’inflammation et du métabolisme des xénobiotiques . Nos travaux sont les premiers visant à cartographier l’expression génique et protéique d’AhR et de ses gènes cibles, à la fois au fur et à mesure de l’avancement de la grossesse, de la différenciation des trophoblastes primaires ainsi que des cellules bronchiques primaires . Ces données fondamentales ont une importance cruciale pour la compréhension ultérieure des effets après exposition à des polluants environnementaux

    The Aryl Hydrocarbon Receptor and the Nervous System

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    International audienceThe aryl hydrocarbon receptor (or AhR) is a cytoplasmic receptor of pollutants. It translocates into the nucleus upon binding to its ligands, and forms a heterodimer with ARNT (AhR nuclear translocator). The heterodimer is a transcription factor, which regulates the transcription of xenobiotic metabolizing enzymes. Expressed in many cells in vertebrates, it is mostly present in neuronal cell types in invertebrates, where it regulates dendritic morphology or feeding behavior. Surprisingly, few investigations have been conducted to unravel the function of the AhR in the central or peripheral nervous systems of vertebrates. In this review, we will present how the AhR regulates neural functions in both invertebrates and vertebrates as deduced mainly from the effects of xenobiotics. We will introduce some of the molecular mechanisms triggered by the well-known AhR ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which impact on neuronal proliferation, differentiation, and survival. Finally, we will point out the common features found in mice that are exposed to pollutants, and in AhR knockout mice
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