61 research outputs found

    G-Protein Coupled Hormone Receptors of the Hypothalamic-Pituitary-Gonadal Axis are Targets of Endocrine Disrupting Chemicals

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    Endocrine-disrupting chemicals have received significant concern, since they ubiquitously persist in the environment and are able to induce adverse effects on health, and more particularly on reproductive function. Most of the studies focused on nuclear hormone receptors as mediators of sex steroid hormones signaling. However, there are increasing evidences that peptides hormones of the Hypothalamo-Pituitary-Gonadal axis are targets of endocrine-disrupting chemicals (as Gonadotropin-Releasing Hormone, Follicle-Stimulating Hormone, Luteinizing Hormone…). The majority of these hormones act on G protein-coupled membrane receptors. This review summarizes the effects of endocrine-disrupting chemicals on homeostasis of peptides hormone of Hypothalamo-Pituitary-Gonadal axis and on their G protein-coupled membrane receptors signaling revealed by experimental, clinical, and epidemiological studies in human

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    Uluslararası Bakalorya Programı, A1 dersi Türk Dili ve Edebiyatı alanında ele alınan bu tezde, Orhan Kemal'in Gurbet Kuşları adlı yapıtında göç olgusu nedenleri ve sonuçlarıyla beraber incelenmiştir. Göç olgusuyla değişen toplumsal yapı, ekonomik ve kültürel farklılıklar çerçevesinde değerlendirilmiştir. Bu tezin amacı, göç olgusunun toplumsal yapıda alt sınıf ve üst sınıflardaki bireyler üzerindeki etkilerini ortaya koymaktır. Üç ana bölümden oluşan tezin ilk bölümünde yapıta adını veren Gurbet Kuşları kavramı üzerinde durulmuştur. Köylülerin aidiyetsizliği ve uyum sorunu bu bölümde aktarılmıştır. Tezin ikinci bölümünde ise köylülerin köyden kente göç sürecinde yaşadıkları kadın ve erkek figürler üzerinden neden ve sonuçlarıyla işlenmiştir. Tezin üçüncü bölümünde şehirliler başlığı altından genel olarak şehirde – İstanbul – yaşayan insanların göç sürecinde köylülerle yaşadıkları uyumsuzluk ve çatışmalara yer verilmektedir. Çalışmada göç sürecinde şehre yerleşen figürlerin şehirlilerle aralarındaki ekonomik ve kültürel farklılıkların sınıflar arasında geçişe olanak tanımadığı sonucuna varılmıştır

    The mineralocorticoid receptor: insights into its molecular and (patho)physiological biology

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    The last decade has witnessed tremendous progress in the understanding of the mineralocorticoid receptor (MR), its molecular mechanism of action, and its implications for physiology and pathophysiology. After the initial cloning of MR, and identification of its gene structure and promoters, it now appears as a major actor in protein-protein interaction networks. The role of transcriptional coregulators and the determinants of mineralocorticoid selectivity have been elucidated. Targeted oncogenesis and transgenic mouse models have identified unexpected sites of MR expression and novel roles for MR in non-epithelial tissues. These experimental approaches have contributed to the generation of new cell lines for the characterization of aldosterone signaling pathways, and have also facilitated a better understanding of MR physiology in the heart, vasculature, brain and adipose tissues. This review describes the structure, molecular mechanism of action and transcriptional regulation mediated by MR, emphasizing the most recent developments at the cellular and molecular level. Finally, through insights obtained from mouse models and human disease, its role in physiology and pathophysiology will be reviewed. Future investigations of MR biology should lead to new therapeutic strategies, modulating cell-specific actions in the management of cardiovascular disease, neuroprotection, mineralocorticoid resistance, and metabolic disorders

    Prodrugs approach for the synthesis of 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) inhibitors : potential antitubercular drugs

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    De nos jours la tuberculose est une des maladies les plus meurtrières au monde. Un problème majeur est que l’agent pathogène responsable de cette maladie (Mycobacterium tuberculosis) a développé des mécanismes de résistances envers les médicaments actuels. Il devient donc urgent de trouver d’autres cibles pour développer de nouveaux antituberculeux. La biosynthèse des isoprénoïdes pourrait en être une. Les précurseurs biologiques de tous les isoprénoïdes sont l’IPP et le DMAPP qui sont synthétisés selon deux voies. La voie du mévalonate, présente chez l’Homme et la voie du méthylérythritol phosphate (MEP) laquelle est présente chez M. tuberculosis et absente chez l’homme. La fosmidomycine et la fosfoxacine, deux inhibiteurs de la désoxyxylulose phosphate réductoisomérase (DXR), deuxième enzyme de la voie du MEP ne permet pas d’inhiber la croissance de la mycobactérie. Cela est dû à l’absence de pénétration de ces composés polaires au sein de la bactérie. Pour pallier à ces problèmes de biodisponibilité, nous avons synthétisé des prodrogues lipophiles de type cycloSaligényle et arylphosphoramidate d’inhibiteurs de la DXR. Certains composés sont inhibent la croissance d’une mycobactérie non-pathogène, Mycobacterium smegmatis.Today, tuberculosis is one of most murderous infectious diseases in the world. This disease is caused by the mycobacterium : Mycobacterium tuberculosis which is becoming more and more resistant towards antitubercular drugs. Therefore, it is urgent to find inovative targets for the development of new antitubercular drugs. The biosynthesis of isoprenoids represents such a target. The biological precursors of all isoprenoids are IPP and DMAPP which are synthesized via two pathways the mevalonate pathway, which is present in human and the methylerythritol phosphate (MEP) pathway which is present in M. tuberculosis. but absent in human. Fosmidomycin and fosfoxacine, two natural inhibitors of the deoxyxylulose phosphate reductoisomerase (DXR), the second enzyme of MEP pathway, but they do not affect the growth of Mycobacterium tuberculosis cells, due to a lack of uptake of the polar drugs by the bacteria. To overcome this absence of the mycobacterial cell watll crossing of these compounds, we synthesized lipophilic cycloSaligenyl and arylphosphoramidate prodrugs of DXR inhibitors. Some compounds inhibit the growth of Mycobacterium smegmatis, a non-pathogenic model of mycobacterium

    Synthèse de prodrogues d'inhibiteurs de la 1-désoxy-D-xylulose 5-phosphate réductoisomérase (DXR) : des agents antituberculeux potentiels

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    Today, tuberculosis is one of most murderous infectious diseases in the world. This disease is caused by the mycobacterium : Mycobacterium tuberculosis which is becoming more and more resistant towards antitubercular drugs. Therefore, it is urgent to find inovative targets for the development of new antitubercular drugs. The biosynthesis of isoprenoids represents such a target. The biological precursors of all isoprenoids are IPP and DMAPP which are synthesized via two pathways the mevalonate pathway, which is present in human and the methylerythritol phosphate (MEP) pathway which is present in M. tuberculosis. but absent in human. Fosmidomycin and fosfoxacine, two natural inhibitors of the deoxyxylulose phosphate reductoisomerase (DXR), the second enzyme of MEP pathway, but they do not affect the growth of Mycobacterium tuberculosis cells, due to a lack of uptake of the polar drugs by the bacteria. To overcome this absence of the mycobacterial cell watll crossing of these compounds, we synthesized lipophilic cycloSaligenyl and arylphosphoramidate prodrugs of DXR inhibitors. Some compounds inhibit the growth of Mycobacterium smegmatis, a non-pathogenic model of mycobacterium.De nos jours la tuberculose est une des maladies les plus meurtrières au monde. Un problème majeur est que l’agent pathogène responsable de cette maladie (Mycobacterium tuberculosis) a développé des mécanismes de résistances envers les médicaments actuels. Il devient donc urgent de trouver d’autres cibles pour développer de nouveaux antituberculeux. La biosynthèse des isoprénoïdes pourrait en être une. Les précurseurs biologiques de tous les isoprénoïdes sont l’IPP et le DMAPP qui sont synthétisés selon deux voies. La voie du mévalonate, présente chez l’Homme et la voie du méthylérythritol phosphate (MEP) laquelle est présente chez M. tuberculosis et absente chez l’homme. La fosmidomycine et la fosfoxacine, deux inhibiteurs de la désoxyxylulose phosphate réductoisomérase (DXR), deuxième enzyme de la voie du MEP ne permet pas d’inhiber la croissance de la mycobactérie. Cela est dû à l’absence de pénétration de ces composés polaires au sein de la bactérie. Pour pallier à ces problèmes de biodisponibilité, nous avons synthétisé des prodrogues lipophiles de type cycloSaligényle et arylphosphoramidate d’inhibiteurs de la DXR. Certains composés sont inhibent la croissance d’une mycobactérie non-pathogène, Mycobacterium smegmatis

    In Utero Exposure to Maternal Diabetes Is Associated With Early Abnormal Vascular Structure in Offspring

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    Aim/hypothesis:In utero exposure to maternal diabetes increases the risk of developing hypertension and cardiovascular disorders during adulthood. We have previously shown that this is associated with changes in vascular tone in favor of a vasoconstrictor profile, which is involved in the development of hypertension. This excessive constrictor tone has also a strong impact on vascular structure. Our objective was to study the impact of in utero exposure to maternal diabetes on vascular structure and remodeling induced by chronic changes in hemodynamic parameters.Methods and Results: We used an animal model of rats exposed in utero to maternal hyperglycemia (DMO), which developed hypertension at 6 months of age. At a pre-hypertensive stage (3 months of age), we observed deep structural modifications of the vascular wall without any hemodynamic perturbations. Indeed, in basal conditions, resistance arteries of DMO rats are smaller than those of control mother offspring (CMO) rats; in addition, large arteries like thoracic aorta of DMO rats have an increase of smooth muscle cell attachments to elastic lamellae. In an isolated perfused kidney, we also observed a leftward shift of the flow/pressure relationship, suggesting a rise in renal peripheral vascular resistance in DMO compared to CMO rats. In this context, we studied vascular remodeling in response to reduced blood flow by in vivo mesenteric arteries ligation. In DMO rats, inward remodeling induced by a chronic reduction in blood flow (1 or 3 weeks after ligation) did not occur by contrast to CMO rats in which arterial diameter decreased from 428 ± 17 μm to 331 ± 20 μm (at 125 mmHg, p = 0.001). In these animals, the transglutaminase 2 (TG2) pathway, essential for inward remodeling development in case of flow perturbations, was not activated in low-flow (LF) mesenteric arteries. Finally, in old hypertensive DMO rats (18 months of age), we were not able to detect a pressure-induced remodeling in thoracic aorta.Conclusions: Our results demonstrate for the first time that in utero exposure to maternal diabetes induces deep changes in the vascular structure. Indeed, the early narrowing of the microvasculature and the structural modifications of conductance arteries could be a pre-emptive adaptation to fetal programming of hypertension

    Sex Bias in Differentiated Thyroid Cancer

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    International audienceDifferentiated thyroid cancers are more frequent in women than in men. These different frequencies may depend on differences in patient’s behavior and in thyroid investigations. However, an impact on sexual hormones is likely, although this has been insufficiently elucidated. Estrogens may increase the production of mutagenic molecules in the thyroid cell and favor the proliferation and invasion of tumoral cells by regulating both the thyrocyte enzymatic machinery and the inflammatory process associated with tumor growth. On the other hand, the worse prognosis of thyroid cancer associated with the male gender is poorly explained

    Mineralocorticoid receptor overexpression in embryonic stem cell-derived cardiomyocytes increases their beating frequency.: cardiac MR and pacemaker channel HCN1

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    International audienceAIMS: Cardiac mineralocorticoid receptor (MR) activation triggers adverse cardiovascular events that could be efficiently prevented by mineralocorticoid antagonists. To gain insights into the pathophysiological role of MR function, we established embryonic stem (ES) cell lines from blastocysts of transgenic mice overexpressing the human MR driven by its proximal P1 or distal P2 promoter and presenting with cardiomyopathy, tachycardia, and arrhythmia. Cardiomyocyte differentiation allowed us to investigate the molecular mechanisms contributing to MR-mediated cardiac dysfunction. METHODS AND RESULTS: During cardiac differentiation, wild-type (WT) and recombinant ES cell cultures and excised beating patches expressed endogenous MR along with cardiac gene markers. The two-fold increase in MR protein detected in P1.hMR and P2.hMR cardiomyocytes led to a parallel increase in the spontaneous beating frequency of hMR-overexpressing cardiomyocytes compared with WT. The MR-mediated chronotropic effect was ligand-independent, could be partially repressed by spironolactone, and was accompanied by a significant two- to four-fold increase in mRNA and protein levels of the pacemaker channel HCN1, generating depolarizing If currents, thus revealing a potential new MR target. This was associated with modification in the expression of HCN4, the inward-rectifier potassium channel Kir2.1, and the L-type voltage-dependent calcium channel Cav1.2. CONCLUSION: We demonstrate that the amplification of MR signalling in ES-derived cardiomyocytes has a major impact on cardiomyocyte contractile properties through an important remodelling of ion channel expression, contributing to arrhythmias. Our results highlight the prominent role of MR function in cardiac physiology and support the benefit of MR antagonists in the management of cardiac dysfunctions

    : Mineralocorticoid receptor as neuroprotective factor

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    International audienceMineralocorticoid receptor (MR), highly expressed in the hippocampus, binds corticosteroid hormones and coordinately participates, with the glucocorticoid receptor, to the control of stress responses, memorization, and behavior. To investigate the impact of MR in neuronal survival, we generated murine embryonic stem (ES) cells that overexpress human MR (hMR) (P1-hMR) and are induced to differentiate into mature neurons. We showed that recombinant MR expression increased throughout differentiation and is 2-fold higher in P1-hMR ES-derived neurons compared with wild-type controls, whereas glucocorticoid receptor expression was unaffected. Although proliferation and early neuronal differentiation were comparable in P1-hMR and wild-type ES cells, MR overexpression was associated with higher late neuronal marker expression (microtubule-associated protein 2 and β-tubulin III). This was accompanied by a shift towards neuron survival with an increased ratio of anti- vs. proapoptotic molecules and 50% decreased caspase 3 activity. Knocking down MR overexpression by small interfering RNA drastically reversed neuroprotective effects with reduced Bcl(2)/Bax ratio and decreased microtubule-associated protein 2 expression. P1-hMR neurons were protected against oxidative stress-induced apoptosis through reduced caspase 3 activation and drastically increased Bcl(2)/Bax ratio and β-tubulin III expression. We demonstrated the involvement of MR in neuronal differentiation and survival and identify MR as an important neuroprotective mediator opening potential pharmacological strategies
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