Is There a Relationship between Ovarian Epithelial Dysplasia and Infertility?

Aim. Ovarian epithelial dysplasia was initially described in material from prophylactic oophorectomies performed in patients at genetic risk of ovarian cancer. Similar histopathological abnormalities have been revealed after ovulation stimulation. Since infertility is also a risk factor for ovarian neoplasia, the aim of this study was to study the relationship between infertility and ovarian dysplasia. Methods. We blindly reviewed 127 histopathological slides of adnexectomies or ovarian cystectomies according to three groups—an exposed group to ovulation induction (n = 30), an infertile group without stimulation (n = 35), and a spontaneously fertile control group (n = 62)—in order to design an eleven histopathological criteria scoring system. Results. The ovarian dysplasia score was significantly higher in exposed group whereas dysplasia score was low in infertile and control groups (resp., 8.21 in exposed group, 3.69 for infertile patients, and 3.62 for the controls). In the subgroup with refractory infertility there was a trend towards a more severe dysplasia score (8.53 in ovulation induction group and 5.1 in infertile group). Conclusion. These results raise questions as to the responsibility of drugs used to induce ovulation and/or infertility itself in the genesis of ovarian epithelial dysplasia

Actin reduction by MsrB2 is a key component of the cytokinetic abscission checkpoint and prevents tetraploidy

International audienceAbscission is the terminal step of cytokinesis leading to the physical separation of the daughter cells. In response to the abnormal presence of lagging chromatin between dividing cells, an evolutionarily conserved abscission/NoCut checkpoint delays abscission and prevents formation of binucleated cells by stabilizing the cytokinetic intercellular bridge (ICB). How this bridge is stably maintained for hours while the checkpoint is activated is poorly understood and has been proposed to rely on F-actin in the bridge region. Here, we show that actin polymerization is indeed essential for stabilizing the ICB when lagging chromatin is present, but not in normal dividing cells. Mechanistically, we found that a cytosolic pool of human methionine sulfoxide reductase B2 (MsrB2) is strongly recruited at the midbody in response to the presence of lagging chromatin and functions within the ICB to promote actin polymerization there. Consistently, in MsrB2-depleted cells, F-actin levels are decreased in ICBs, and dividing cells with lagging chromatin become binucleated as a consequence of unstable bridges. We further demonstrate that MsrB2 selectively reduces oxidized actin monomers and thereby counteracts MICAL1, an enzyme known to depolymerize actin filaments by direct oxidation. Finally, MsrB2 colocalizes and genetically interacts with the checkpoint components Aurora B and ANCHR, and the abscission delay upon checkpoint activation by nuclear pore defects also depends on MsrB2. Altogether, this work reveals that actin reduction by MsrB2 is a key component of the abscission checkpoint that favors F-actin polymerization and limits tetraploidy, a starting point for tumorigenesis

Absence of detection of highly pathogenic H5N1 in migratory waterfowl in southern France in 2005–2006

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Optineurin Regulates the Interferon Response in a Cell Cycle-Dependent Manner

International audienceViral invasion into a host is initially recognized by the innate immune system, mainly through activation of the intracellular cytosolic signaling pathway and coordinated activation of inter-feron regulatory factor 3 (IRF3) and nuclear factor kappa B (NF-κB) transcription factors that promote type I interferon gene induction. The TANK-binding Kinase 1 (TBK1) phos-phorylates and activates IRF3. Here, we show that Optineurin (Optn) dampens the antiviral innate immune response by targeting the deubiquitinating enzyme CYLD to TBK1 in order to inhibit its enzymatic activity. Importantly, we found that this regulatory mechanism is abolished at the G2/M phase as a consequence of the nuclear translocation of CYLD and Optn. As a result, we observed, at this cell division stage, an increased activity and phosphoryla-tion of TBK1 that lead to its relocalization to mitochondria and to enhanced interferon production , suggesting that this process, which relies on Optn function, might be of major importance to mount a preventive antiviral response during mitosis. The innate immune system has evolved to detect and neutralize viral invasion. Triggering of this defense mechanism relies on the production and secretion of soluble factors that stimulate an intracellular antiviral defense mechanism. The protein Optineurin was shown to negatively regulate this process. Importantly, we discovered the mechanism by which Optineurin inhibits antiviral activity and showed that this regulation is prevented during a critical step of cell division leading to enhancement of the cellular defense mechanism. This paper shows that the antiviral immune system is controlled during the cell cycle and that Optineurin-mediated induction of this system might serve to protect cells from infection during cell division

Regulatory and Pathogenic Mechanisms in Human Autoimmune Myasthenia Gravis

International audienceThe thymus is frequently hyperplastic in young female myasthenia gravis (MG) patients presenting with anti-acetylcholine receptor (AChR) antibodies. This thymic pathology is characterized by the presence of ectopic germinal centers (GCs) containing B cells involved at least partially in the production of pathogenic anti-AChR antibodies. Our recent studies have furthered our understanding of the mechanisms leading to GC formation in the hyperplastic thymus. First, we showed that CXCL13 and CCL21, chemokines involved in GC formation, are overexpressed in MG thymus. Second, we demonstrated an increase in pro-inflammatory activity in the thymus from MG patients and its partial normalization by glucocorticoids, as evidenced by gene expression profile. Third, we found that pro-inflammatory cytokines are able to upregulate the expression of AChR subunits in thymic epithelial and myoid cells. Fourth, we showed that the function of T regulatory (Treg) cells, whose role is to downregulate the immune response, is severely impaired in the thymus of MG patients; such a defect could explain the chronic immune activation observed consistently in MG thymic hyperplasia. Altogether, these new data suggest that CXCL13 and CCL21, which are produced in excess in MG thymus, attract peripheral B cells and activated T cells, which are maintained chronically activated in the inflammatory thymic environment because of the defect in suppressive activity of Treg cells. Presence of AChR in the thymus and upregulation of its expression by the pro-inflammatory environment contribute to the triggering and maintenance of the anti-AChR autoimmune response

Accession Numbers

<p>ND, not determined.</p