Implication de la signalisation de la tyrosine kinase Yes dans la carcinogenèse hépatique

Le carcinome hépatocellulaire (CHC) est la première néoplasie létale du foie, représentant 80 à 90% des cas. Actuellement, la majeure partie des patients bénéficient de solutions thérapeutiques avec des efficacités très modestes. La haute variété étiologique, l’hétérogénéité des tumeurs ainsi que l’absence de médiateurs oncogéniques clés connus dans le développement de cette pathologie sont responsables du manque d’options thérapeutiques. À partir d’un crible génétique du kinome humain, nous avons identifié la tyrosine kinase Yes comme un acteur majeur de la prolifération des cellules de CHC. Yes appartient à la famille des kinases Src qui contrôlent de nombreux processus cellulaires notamment la prolifération, la motilité et la survie. La sur-expression ou activation anormale de Yes est retrouvée dans de nombreux cancers et est souvent associée à un mauvais pronostic. Nous avons démontré par des expériences in vitro et in vivo l’activité pro-proliférative de Yes ainsi que son potentiel oncogénique. Notamment, dans un modèle murin de carcinogenèse hépatique induit par le diéthylnitrosamine, la déplétion génétique de Yes abolit totalement la formation de tumeurs. Grâce aux profils transcriptionnels obtenus dans plusieurs modèles cellulaires de CHC, nous avons découvert que l’activité de Yes est associée à une augmentation des signatures géniques des régulateurs transcriptionnels YAP et TAZ ainsi que du facteur transcriptionnel c-Myc. Ces observations ont abouti à identifier YAP, TAZ et c-Myc comme des nouveaux substrats de la tyrosine kinase Yes. Nous avons montré que la phosphorylation par Yes de YAP et TAZ médie leur recrutement dans le noyau ce qui conduit à une hausse de leur activité transcriptionnelle. Nous avons d’ailleurs confirmé l’importance de YAP et TAZ dans les propriétés prolifératives de Yes, notamment dans différents modèles murins de carcinogenèse hépatique. De manière intéressante, nous avons observé que près de 50% de CHCs humains présentent une activation anormale des kinases Src qui corrèle avec la phosphorylation et activation de YAP. Enfin, nous avons observé in vitro et in vivo que Yes stabilise c-Myc. En effet, l’expression transgénique de Yes constitutivement actif dans des hépatocytes entraine la stabilisation de c-Myc à des stades précoces du développement tumoral et une induction de plusieurs de ses gènes cibles à des stades plus tardifs. En plus de leur synergie d’action, cette étude propose que la tyrosine Yes intervient dans les propriétés oncogéniques de c-Myc. Finalement, nous avons découvert que la kinase Yes joue un rôle dans la progression de la stéatose hépatique. En effet, la progression de la pathologie est abolie à la suite de la déplétion de Yes ou suivant l’inhibition pharmacologique des kinases Src. De plus, la survie des cellules tumorales face à leur élimination par le système immunitaire semble être favorisé par la signalisation Yes qui induit l’expression des points de contrôle immuns PD-L1/2. En conclusion nous avons découvert et caractérisé trois nouveaux effecteurs clés de la signalisation oncogénique de la tyrosine kinase Yes dans le CHC. D’ailleurs, la signature génique induite par Yes permet de prédire la survie des patients atteints de CHC. Ces données fournissent de robustes évidences qui placent la tyrosine kinase Yes comme une cible thérapeutique de choix pour la maladie du CHC.Hepatocellular carcinoma (HCC) is the first lethal neoplasia of the liver, representing 80 to 90% of cases. Currently, for most patients the therapeutic option only provides modest efficiencies. The high etiological variety and heterogeneity of the tumors as well as the absence of known key oncogenic mediator in the development of this pathology is mainly responsible for the lack of therapeutic option. Based on a genetic screen of the human kinome, we identified the tyrosine kinase Yes as a major player in the proliferation of HCC cells. Yes belongs to the family of Src kinases which control many cellular processes including proliferation, motility and survival. The over-expression or abnormal activation of Yes is detected in many cancers and is often associated with poor prognosis. We have demonstrated in vitro and in vivo the pro-proliferative activity of Yes as well as its oncogenic potential. In particular, in a mouse model of hepatic carcinogenesis induced by diethylnitrosamine, the genetic depletion of Yes completely abolishes the formation of tumors. Thanks to the transcriptional profiles obtained in several cellular models of CHC, we discovered that the activity of Yes is associated with an increase in the gene signatures of the transcriptional regulators YAP and TAZ as well as of the transcriptional factor c-Myc. These observations led to the identification of YAP, TAZ and c-Myc as new substrates for the tyrosine kinase Yes. We have shown that the phosphorylation of YAP and TAZ by Yes mediates their recruitment into the nucleus associated with an increase in their transcriptional activity. We have also confirmed the importance of YAP and TAZ in the proliferative properties of Yes in various mouse models of hepatocarcinogenesis. Interestingly, we observed that nearly 50% of human CHCs exhibit an abnormal activation of Src kinases that correlates with phosphorylation and activation of YAP. Moreover, in vitro and in vivo experiments revealed that Yes stabilizes c-Myc. Indeed, the transgenic expression of constitutively active Yes into hepatocytes leads to the accumulation of c-Myc protein at early stages of tumor development and to the induction of several of its target genes at later stages. In addition to their synergistic action, this study suggests that Yes is involved in the oncogenic properties of c-Myc. Finally, we discovered that Yes kinase plays a role in the progression of fatty liver diseases. Indeed, the progression of the pathology is abolished following the depletion of Yes or the pharmacological inhibition of Src kinases. In addition, the survival of Yes-active tumor cells is associated with the induction of PD-L1/2 immune checkpoints that protect cells from immune elimination. In conclusion, we have discovered and characterized three new key effectors of the oncogenic tyrosine kinase Yes in HCC. Interestingly, the gene signature induced by Yes can predict the survival of patients with HCC. These data provide strong evidence for targeting the tyrosine kinase Yes in HCC

NrsZ: a novel, processed, nitrogen-dependent, small non-coding RNA that regulates Pseudomonas aeruginosa PAO1 virulence.

The opportunistic pathogen Pseudomonas aeruginosa PAO1 has a remarkable capacity to adapt to various environments and to survive with limited nutrients. Here, we report the discovery and characterization of a novel small non-coding RNA: NrsZ (nitrogen-regulated sRNA). We show that under nitrogen limitation, NrsZ is induced by the NtrB/C two component system, an important regulator of nitrogen assimilation and P. aeruginosa's swarming motility, in concert with the alternative sigma factor RpoN. Furthermore, we demonstrate that NrsZ modulates P. aeruginosa motility by controlling the production of rhamnolipid surfactants, virulence factors notably needed for swarming motility. This regulation takes place through the post-transcriptional control of rhlA, a gene essential for rhamnolipids synthesis. Interestingly, we also observed that NrsZ is processed in three similar short modules, and that the first short module encompassing the first 60 nucleotides is sufficient for NrsZ regulatory functions

Pigment conformation and pigment–protein interactions in the reconstituted Lhcb4 antenna protein

Resonance Raman spectra of the native Lhcb4 antenna protein are compared with those of a recombinant protein prepared by in vitro refolding of its polypeptide, over‐expressed in Escherichia coli, with added pigments [Giuffra et al. (1996) Eur. J. Biochem. 238, 112–120]. The results indicate that the native pigment conformation is reproduced almost perfectly in the reconstituted protein, with only small differences which are attributed to a slight shift in the Soret absorption peak of two or more chlorophylls. This procedure therefore represents a model system for the investigation of site‐directed mutant LHC proteins, which are otherwise very difficult to obtain

Novel targets of the CbrAB/Crc carbon catabolite control system revealed by transcript abundance in Pseudomonas aeruginosa.

The opportunistic human pathogen Pseudomonas aeruginosa is able to utilize a wide range of carbon and nitrogen compounds, allowing it to grow in vastly different environments. The uptake and catabolism of growth substrates are organized hierarchically by a mechanism termed catabolite repression control (Crc) whereby the Crc protein establishes translational repression of target mRNAs at CA (catabolite activity) motifs present in target mRNAs near ribosome binding sites. Poor carbon sources lead to activation of the CbrAB two-component system, which induces transcription of the small RNA (sRNA) CrcZ. This sRNA relieves Crc-mediated repression of target mRNAs. In this study, we have identified novel targets of the CbrAB/Crc system in P. aeruginosa using transcriptome analysis in combination with a search for CA motifs. We characterized four target genes involved in the uptake and utilization of less preferred carbon sources: estA (secreted esterase), acsA (acetyl-CoA synthetase), bkdR (regulator of branched-chain amino acid catabolism) and aroP2 (aromatic amino acid uptake protein). Evidence for regulation by CbrAB, CrcZ and Crc was obtained in vivo using appropriate reporter fusions, in which mutation of the CA motif resulted in loss of catabolite repression. CbrB and CrcZ were important for growth of P. aeruginosa in cystic fibrosis (CF) sputum medium, suggesting that the CbrAB/Crc system may act as an important regulator during chronic infection of the CF lung

Thermal analysis of parts produced by L-PBF and correlation with dimensional accuracy

Laser-Power Bed Fusion (L-PBF) is continuing to grow in use among the industrial field. This process allows the manufacturing of parts with complex geometry, good dimensional accuracy, and few post-processing steps. However, deviations can still be observed on the final parts. It is known in the literature that all of these deviations can be imputed to some extent to thermal phenomena such as overheating or thermal gradient through residual stress relaxation. The objective of this study is to reach a better understanding of the influence of the thermal properties on the dimensional accuracy of parts produced by L-PBF. To do so, an infrared camera has been instrumented inside the machine, allowing the determination of the temperature of parts during the process. Thin walls with different process parameters (laser power, scanning speed…) and nominal dimensions were manufactured and measured afterwards with a coordinate measuring machine (CMM). Thermal acquisitions were performed at different moments during the fabrication and give access to the cooling rate of the observed parts. Least square fitting has been used to approximate the cooling rate function and returns characteristic times that are used to compare the different manufacturing configurations. In the end, a correlation has been established between the process parameters, the thermal parameters, and the dimensional accuracy of the parts. Form deviations, possibly due to residual stress, have only been observed on the thinnest wall, which is also the part with the highest measured thermal gradients. Other form deviations were due to roughness

A WXW Motif Is Required for the Anticancer Activity of the TAT-RasGAP317-326 Peptide.

TAT-RasGAP317-326, a cell-permeable 10-amino acid-long peptide derived from the N2 fragment of p120 Ras GTPase-activating protein (RasGAP), sensitizes tumor cells to apoptosis induced by various anticancer therapies. This RasGAP-derived peptide, by targeting the deleted in liver cancer-1 (DLC1) tumor suppressor, also hampers cell migration and invasion by promoting cell adherence and by inhibiting cell movement. Here, we systematically investigated the role of each amino acid within the RasGAP317-326 sequence for the anticancer activities of TAT-RasGAP317-326. We report here that the first three amino acids of this sequence, tryptophan, methionine, and tryptophan (WMW), are necessary and sufficient to sensitize cancer cells to cisplatin-induced apoptosis and to reduce cell migration. The WMW motif was found to be critical for the binding of fragment N2 to DLC1. These results define the interaction mode between the active anticancer sequence of RasGAP and DLC1. This knowledge will facilitate the design of small molecules bearing the tumor-sensitizing and antimetastatic activities of TAT-RasGAP317-326

Laser heat treatment of martensitic steel and dual-phase steel with high martensite content

Laser heat treatment of galvanised steels with a martensite content superior to 80% were performed on a 1 cm wide area over an extensive temperature range [620 K - 1350 K]. The material softening induced is studied through uniaxial tensile testing and SEM microstructural observation. A treatment temperature close to Ac3 yields a massive increase in the ductility of the specimens while reducing the mechanical strength. This change in mechanical properties is associated with the nucleation of new austenite islands and the vanishing of the initial martensite laths. The results presented in this paper pave the way to localised variations of the strength-ductility trade-off, which could be useful for several industrial applications, particularly for enabling plastic forming or stamping of the martensitic steel sheets at low temperature.ANR JCJC SCOLASTIC project (grant no. 16-CE08-0009

Empirical research on the impact and experience of open prisons: state of the field and future directions

The term ‘open prison’ can be used to mean different things depending on the jurisdiction or institution, but generally refers to a prison into which residents are not fully or always locked.1 Relative to their ‘closed’ counterparts, open prisons generally afford detainees a greater connection to the outside world, often through access to family and day release for employment, volunteering and education. As such, progressive prison reformers and scholars often tout the potential benefits of open conditions for the wellbeing and reintegration of people in custody2 — relative, at least, to the generally deleterious effect of entirely closed regimes.3 Yet, compared with research on closed prisons, there remains only a modest quantity of empirical work on open prisons, even considering the low proportion of incarcerated people in open prisons in most countries.4 Similarly, few studies attend to the experience of staffing open prisons, despite a burgeoning literature on prison officers.5 There must be further research on the impact and experiences of living or working in open prisons to enhance our understanding of different prison regimes and inform penal policy

Analyse in vitro de l’efficacité de la lithotritie laser : quel modèle utiliser ?

L’étude in vitro de la lithotritie laser (LL) utilise des calculs humains (CH) ou synthétiques (CS). Devant l’augmentation de la pulvérisation laser (Dusting), peu d’échantillons humains sont disponibles. Les CS sont donc privilégiés, confectionnés par mélange d’eau et de plâtre, avec la problématique de leur réhydratation lors des LL. L’objectif était de comparer les volumes d’ablation (VA) entre CS homogènes (CSHo) ou hétérogènes(CSHe), et par rapport au poids ablaté (PA).Bourse de Recherche AFU 201

Acoustic false ceiling in wide rooms, realized by an innovative textile system

The aim of this article is the study of wide rooms’ acoustic false ceilings. In order to improve indoor acoustic comfort, it is possible to install an acoustic false ceiling. Many technical solutions are used to improve the inner room quality in terms of reverberation time and speech intelligibility. Restaurants and dining halls often can have acoustic problems caused by uncontrolled background disturbing noise. Indoor comfort can be seriously impaired in crowded rooms with many speakers, such as in restaurants and dining halls: the background noise produced by people talking damages the speech intelligibility level. If the speaker cannot be heard by his listener, he will speak louder. The speaker’s increasing voice power will gradually intensify the background noise producing a domino effect (cocktail party effect). In this case study we show the use of a brand new textile false ceiling system. This solutionhas just been installed in the Centre Hospitalier Universitaire Vaudois (Lausanne) new restaurant (1800 m2) that can host 800 people. The innovative textile system, designed for this project, is composed of an aluminium structure within a shaped rock wool panel, enfolded by stretched EPS “acoustically transparent” fabric. This system, suspended from the ceiling and held by metallic lateral supports, improves the room acoustic quality, creating a nice dynamic effect as well. The installation of this system began in July 2014 and was completed in April 2015. We used the CATT-Acoustic software to analyse the room acoustic behaviour, the reverberation time and speech intelligibility