Methylated DNA recognition during the reversal of epigenetic silencing is regulated by cysteine and cerine residues in the Epstein-Barr Virus lytic switch protein

Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with various malignancies, including Burkitt's lymphoma and nasopharyngeal carcinoma. Like all herpesviruses, the EBV life cycle alternates between latency and lytic replication. During latency, the viral genome is largely silenced by host-driven methylation of CpG motifs and, in the switch to the lytic cycle, this epigenetic silencing is overturned. A key event is the activation of the viral BRLF1 gene by the immediate-early protein Zta. Zta is a bZIP transcription factor that preferentially binds to specific response elements (ZREs) in the BRLF1 promoter (Rp) when these elements are methylated. Zta's ability to trigger lytic cycle activation is severely compromised when a cysteine residue in its bZIP domain is mutated to serine (C189S), but the molecular basis for this effect is unknown. Here we show that the C189S mutant is defective for activating Rp in a Burkitt's lymphoma cell line. The mutant is compromised both in vitro and in vivo for binding two methylated ZREs in Rp (ZRE2 and ZRE3), although the effect is striking only for ZRE3. Molecular modeling of Zta bound to methylated ZRE3, together with biochemical data, indicate that C189 directly contacts one of the two methyl cytosines within a specific CpG motif. The motif's second methyl cytosine (on the complementary DNA strand) is predicted to contact S186, a residue known to regulate methyl-ZRE recognition. Our results suggest that C189 regulates the enhanced interaction of Zta with methylated DNA in overturning the epigenetic control of viral latency. As C189 is conserved in many bZIP proteins, the selectivity of Zta for methylated DNA may be a paradigm for a more general phenomenon

First description of pestivirus disease in Rupicapra pyrenaica pyrenaica

Understanding the circulation of pestiviruses in wild ungulates is potentially important to explain variations in the number of animals in these species, and to implement pestivirus control programs in domestic animals. In 2002 in the French Pyrenees, symptoms of amyotrophy and weight loss, associated with bilateral alopecia with hairless and highly pigmented areas on the nose, around the eyes and the ear margins were found in 8 Pyrenean chamois (Rupicapra pyrenaica pyrenaica) between 1 and 9 years old, 6 of which had been captured alive and 2 were found dead. These lesions were uncharacteristic. The intensity of abomasal or lung parasitism varied from one animal to the other. Pestiviruses were isolated in all 6 animals captured alive, but no anti-NS2/3 antibodies were found. Many questions remain on the transitory or persistent nature of the infection, and on the conditions of viral transmission within the Rupicapra genus.Comprendre la circulation de pestivirus chez les ongulés sauvages est potentiellement important pour expliquer les variations d'effectifs dans ces espèces et pour réaliser les programmes de contrôle des pestiviroses atteignant les animaux domestiques. En 2002 dans les Pyrénées ariégeoises, des symptômes d'amyotrophie et d'amaigrissement, associés à des signes d'alopécie bilatérale, avec des zones cutanées glabres et fortement pigmentées sur le chanfrein, le pourtour des yeux et les marges auriculaires ont été observés sur 8 isards (Rupicapra pyrenaica pyrenaica) âgés de 1 à 9 ans, dont 6 avaient été capturés vivants et 2 trouvés morts. Les lésions étaient peu caractéristiques. L'intensité du parasitisme abomasal ou pulmonaire variait d'un individu à l'autre. Un pestivirus a été mis en évidence sur les 6 animaux capturés vivants et un des deux récupérés morts (7 cas sur 8), mais aucun anticorps dirigé contre la protéine NS2/3 n'a été trouvé. De nombreuses questions persistent sur la nature transitoire ou persistante de l'infection et sur les modalités de transmission au sein du genre Rupicapra

Carbonyl reductase 1 catalyzes 20β-reduction of glucocorticoids, modulating receptor activation and metabolic complications of obesity

Carbonyl Reductase 1 (CBR1) is a ubiquitously expressed cytosolic enzyme important in exogenous drug metabolism but the physiological function of which is unknown. Here, we describe a role for CBR1 in metabolism of glucocorticoids. CBR1 catalyzes the NADPH-dependent production of 20 beta-dihydrocortisol (20 beta-DHF) from cortisol. CBR1 provides the major route of cortisol metabolism in horses and is up-regulated in adipose tissue in obesity in horses, humans and mice. We demonstrate that 20 beta-DHF is a weak endogenous agonist of the human glucocorticoid receptor (GR). Pharmacological inhibition of CBR1 in diet-induced obesity in mice results in more marked glucose intolerance with evidence for enhanced hepatic GR signaling. These findings suggest that CBR1 generating 20 beta-dihydrocortisol is a novel pathway modulating GR activation and providing enzymatic protection against excessive GR activation in obesity

Mechanical resistance of patterned BCB bonded joints for MEMS packaging

International audienceAdhesive wafer bonding is an interesting key technology for heterogeneous integration of films or devices coming from different technologies in the view of 3D heterogeneous integration of NEMS/MEMS. An original wafer level MEMS packaging process consists in the transfer of nickel caps from a temporary wafer to the target wafer carrying the devices to be packaged. In this process the polymer used as sealing ring is submitted to a first mechanical loading as the film cap is removed from the donor wafer. It is therefore important to have quantitative data about the mechanical resistance of the bond in order to ensure its integrity after the fabrication process. In this study, wedge insertion method and four-point bending test are used to characterize bonds of silicon wafers without and with a nickel interlayer. The adhesive polymer is a photosensitive benzocyclobutene (BCB) resin patterned into lines either parallel or perpendicular to the crack growth direction. The measured fracture energies completed by observations of the fracture surfaces allows the identification of various parameters influencing the resistance of the stack. A first parameter is the adhesive lines orientation: when BCB lines are perpendicular to the crack growth direction higher adhesion energies are measured than when they are parallel to this direction. A second parameter is the BCB curing atmosphere: adhesive bonds that experienced a curing treatment in N-2 gas have higher fracture resistance than those cured in vacuum. Finally, the addition of a nickel film between the silicon wafer and the BCB adhesive embrittles the mechanical resistance of the bond because Ni has a poor adhesion both on silicon and on BCB. (C) 2013 Published by Elsevier B.V

Diarrhées colibacillaires néonatales du veau

Gastroenterologie bovineNational audienc