Splice variants as novel targets in pancreatic ductal adenocarcinoma

The study was funded by the MolDiagPaCa European Union Framework Programme and CR-UK Programme grant A12008 from CR-UK (C. Chelala, T. Crnogorac-Jurcevic, and N.R. Lemoine). Italian Cancer Genome Project – Ministry of University [FIRB RBAP10AHJB]; Associazione Italiana Ricerca Cancro [grant number: 12182]; FP7 European Community Grant Cam-Pac [no: 602783]; Italian Ministry of Health [FIMPCUP_J33G13000210001]. The funders were not involved in the design of the study, collection, analysis, and interpretation of data and in writing of the manuscript. We thank Tracy Chaplin-Perkins for help with running the Affymetrix experiments

AC/D(eA)C rocks the polymerases.

In this issue of Molecular Cell, two studies (Chen et al., 2013; Schröder et al., 2013) describe how posttranslational modification of RNA polymerases (Pol) I and II by acetylation mediates the transcriptional response to either stress or growth factors

Dynamic embrittlement at intermediate temperature in a Cu-Ni-Si alloy

International audienceThe mechanical properties of a Cu-2.16Ni-0.72Si alloy in a hardened state are investigated at room temperature (RT) and up to 573 K through tensile tests performed at slow and fast straining rates. In the upper temperature range the material ductility exhibits an anomalous behaviour typical of dynamic embrittlement: the ductility decreases with increasing temperature or/and with decreasing straining rate. SEM observations confirm that result: the fracture surfaces of the broken specimens are predominantly of ductile type at RT, while they are covered of many intergranular facets for specimens tested in the upper temperature range at slow straining rate. The role of stress is predominant in the mechanism of embrittlement. A model of dynamic embrittlement controlled by diffusion is used to derive a factor of embrittlement, SDE, related to the testing conditions. This factor appears to be well correlated with the variation of the ductility linked with the testing conditions

Robustness analysis by a probabilistic approach for propagation of uncertainties in a component mode synthesis context

International audienceModelling uncertainties in an industrial application require a thorough knowledge of their sources and types. Uncertainties can be split into aleatory and epistemic types. Using parametric and non-parametric methods successively can be an adapted approach to model these uncertainties types on a given finite elements model (FEM). However, we propose in this paper to proceed more appropriately by introducing a hybrid approach combining the parametric and non-parametric methods. This approach consists of applying, on a given FEM, parametric and non-parametric methods simultaneously with respect to uncertainties types of each model region. Complexity and size of industrial FEMs often impose model reductions. This introduces necessarily the problem of reduction basis robustness. We are interested in the effectiveness of two methods for model reduction in the case of a hybrid model of uncertainties. We consider the case of component mode synthesis (CMS) based on normal modes of clamped interfaces components. Therefore, we analyze robustness of two methods based on improved Craig–Bampton's basis: the first one is enriched by static residual vectors (ESRV), the second one is a variant of the combined approximations method (VCA) adapted to CMS. Finally, a dynamic application on a railway electric motor stator, allows comparing methods' performances in terms of robustness and gain in computing time. Conclusion highlights relevance of the combined approximations method when using a hybrid approach for modelling uncertainties

Herpes Simplex Virus 1 (HSV-1) ICP22 Protein Directly Interacts with Cyclin-Dependent Kinase (CDK) 9 to Inhibit RNA Polymerase II Transcription Elongation

The Herpes Simplex Virus 1 (HSV-1)-encoded ICP22 protein plays an important role in viral infection and affects expression of host cell genes. ICP22 is known to reduce the global level of serine (Ser)2 phosphorylation of the Tyr1Ser2Pro3Thr4Ser5Pro6Ser7 heptapeptide repeats comprising the carboxy-terminal domain (CTD) of the large subunit of RNA polymerase (pol) II. Accordingly, ICP22 is thought to associate with and inhibit the activity of the positive-transcription elongation factor b (P-TEFb) pol II CTD Ser2 kinase. We show here that ICP22 causes loss of CTD Ser2 phosphorylation from pol II engaged in transcription of protein-coding genes following ectopic expression in HeLa cells and that recombinant ICP22 interacts with the CDK9 subunit of recombinant P-TEFb. ICP22 also interacts with pol II in vitro. Residues 193 to 256 of ICP22 are sufficient for interaction with CDK9 and inhibition of pol II CTD Ser2 phosphorylation but do not interact with pol II. These results indicate that discrete regions of ICP22 interact with either CDK9 or pol II and that ICP22 interacts directly with CDK9 to inhibit expression of host cell genes

Ets-1 binds cooperatively to the palindromic Ets-binding sites in the p53 promoter.

Due to its autoinhibition for DNA binding, the Ets-1 transcription factor must interact with partners to enhance its affinity for DNA. In a study on the stromelysin-1 promoter, we showed that Ets-1 binds cooperatively to two Ets-binding sites (EBS) organized in palindrome, thereby circumventing the need for a binding partner to counteract autoinhibition. This leads to the formation of an Ets-1-DNA-Ets-1 ternary complex necessary for promoter activation. Here we show that Ets-1 also binds cooperatively to the EBS palindrome of the human p53 promoter, despite the presence of a degenerate EBS to which Ets-1 cannot otherwise bind. Transcriptional transactivation through this palindrome fully correlates to Ets-1 binding. Thus, the cooperative binding model that we initially proposed for the stromelysin-1 promoter may be a general mechanism of Ets-1 binding to palindromic EBS separated by 4bp and a way to counteract binding site degeneracy

Caspase cleavage of Ets-1 p51 generates fragments with transcriptional dominant-negative function.

Ets-1 is a transcription factor that plays an important role in various physiological and pathological processes, such as development, angiogenesis, apoptosis and tumour invasion. In the present study, we have demonstrated that Ets-1 p51, but not the spliced variant Ets-1 p42, is processed in a caspase-dependent manner in Jurkat T-leukaemia cells undergoing apoptosis, resulting in three C-terminal fragments Cp20, Cp17 and Cp14 and a N-terminal fragment, Np36. In vitro cleavage of Ets-1 p51 by caspase 3 produces fragments consistent with those observed in cells undergoing apoptosis. These fragments are generated by cleavage at three sites located in the exon VII-encoded region of Ets-1 p51. This region is absent from the Ets-1 p42 isoform, which therefore cannot be cleaved by caspases. In Ets-1 p51, cleavage generates C-terminal fragments containing the DNA-binding domain, but lacking the transactivation domain. The Cp17 fragment, the major cleavage product generated during apoptosis, is devoid of transcriptional activity and inhibits Ets-1 p51-mediated transactivation of target genes by competing with Ets-1 p51 for binding to Ets-binding sites present in the target promoters. In the present study, we have demonstrated that caspase cleavage of Ets-1 within the exon VII-encoded region leads to specific down-regulation of the Ets-1 p51 isoform during apoptosis. Furthermore, our results establish that caspase cleavage generates a stable C-terminal fragment that acts as a natural dominant-negative form of the full-length Ets-1 p51 protein