Transient deSUMOylation of IRF2BP proteins controls early transcription in EGFR signaling

Molecular switches are essential modules in signaling networksand transcriptional reprogramming. Here, we describe a role forsmall ubiquitin-related modifier SUMO as a molecular switch inepidermal growth factor receptor (EGFR) signaling. Using quantita-tive mass spectrometry, we compare the endogenous SUMOproteomes of HeLa cells before and after EGF stimulation. Thereby,we identify a small group of transcriptional coregulators includingIRF2BP1, IRF2BP2, and IRF2BPL as novel players in EGFR signaling.Comparison of cells expressing wild type or SUMOylation-deficientIRF2BP1indicates that transient deSUMOylation of IRF2BP proteinsis important for appropriate expression of immediate early genesincludingdual specificity phosphatase1(DUSP1, MKP-1) and thetranscription factor ATF3. We find that IRF2BP1is a repressor,whose transient deSUMOylation on the DUSP1promoter allows—and whose timely reSUMOylation restricts—DUSP1transcription.Our work thus provides a paradigm how comparative SUMOproteome analyses serve to reveal novel regulators in signal trans-duction and transcription

Role of the SENP2 SUMO protease and LCoR in estrogen signalling

Les œstrogènes sont impliqués dans la prolifération des cellules épithéliales du sein normal et l'exposition prolongée à ces hormones s'accompagne d'une augmentation du risque de développement de cancer du sein. Les œstrogènes exercent leurs effets via les récepteurs des œstrogènes (REs). L'activité de ces récepteurs est finement régulée par un grand nombre de cofacteurs transcriptionnels, mais également par les modifications post-traductionnelles. Mon travail de thèse a eu pour objectif la compréhension de l'impact de ces deux niveaux de régulation sur la signalisation œstrogénique. Il a été récemment décrit que la sumoylation affectait de manière drastique l'activité du RE. La sumoylation est une modification dont le caractère réversible est assuré par des isopeptidases appelé SENPs (SENtrin Proteases). Dans une première étude nous avons montré que SENP2 pouvait fortement réprimer l'activité transcriptionnelle dépendante des œstrogènes ainsi que la prolifération cellulaire. Dans une seconde étude, nous nous sommes attelés à mieux caractériser les mécanismes d'action à l'origine du caractère répresseur du cofacteur transcriptionnel LCoR (Ligand-dependent Corepressor). Nous nous sommes plus précisément intéressés aux relations existant entre LCoR et un autre cofacteur du RE, RIP140 (Receptor Interacting Protein of 140 kDa) répresseur majeur de l'activité œstrogénique. Nous avons pu caractériser, outre les modes de recrutement des deux protéines, les modulations d'expression exercées par les deux cofacteurs. L'ensemble de nos travaux identifie de nouveaux cofacteurs des REs et contribue à une meilleure compréhension de la signalisation œstrogénique.Estrogens are involved in the proliferation of normal breast epithelial cells. The prolonged exposure to these hormones comes along with an increase of the risk of breast cancer.development. Estrogen receptors (ERs) mediate the effects of estrogens. The activity of these receptors is finely tuned by a large number of transcriptional cofactors, but also by post-translational modifications. This work aimed at understanding the impact of these regulations on estrogenic signalling. It was recently described that sumoylation could strongly affect ER-dependent activity. SUMO conjugation is a dynamic process which is reversed by SUMO specific proteases also known as SENtrin Proteases (SENPs). In a first study, we investigated the role of SENP2, in ER-dependent transcriptional activity. We showed that SENP2 could acts as a transcriptional cofactor independently of its catalytic activity by strongly repressing ER-dependent transcriptional activity. We also provided evidence for a role in in breast cancer cell line proliferation. In a second part of the work we investigated the mechanism of action of the transcriptional cofactor LCoR (Ligand-dependent Corepressor) with a specific emphasis on the relationship between LCoR and another ER cofactor, RIP140 (Receptor Interacting Protein of 140 kDa). We characterized a crossed expression modulation of the two transcription cofactors. We also depicted an interaction between these two corepressors and a regulation of LCoR activity by RIP140. Our work provides new insights in identifying new coregulators of ER and contributes to a better understanding of both LCoR and RIP140 mechanism of action, and therefore of estrogenic signalling

Volatiles Leaf Oil Constituents of Eucalyptus camaldulensis Dehnh from Algeria

The chemical composition of the essential oil, extracted from Eucalyptus camaldulensis leaves originating from Tizi Ouzou region (north Algeria) has been studied. Analyses were made by GC/FID on two capillary columns, using a non-polar phase (DB1) and another polar one (Carbowax 20M). This essential oil was also analyzed by GC/MS on OV1 capillary columns. The main components identified after this investigation were: p-cymene (22.50%), spathulenol (22.05%), cryptone (16.79%) while 1.8-cineole was identified at a low concentration (1.23%)

Les rôles de la SUMO protéase SENP2 et du corépresseur LCoR dans la signalisation œstrogénique

Les œstrogènes sont impliqués dans la prolifération des cellules épithéliales du sein normal et l'exposition prolongée à ces hormones s'accompagne d'une augmentation du risque de développement de cancer du sein. Les œstrogènes exercent leurs effets via les récepteurs des œstrogènes (REs). L'activité de ces récepteurs est finement régulée par un grand nombre de cofacteurs transcriptionnels, mais également par les modifications post-traductionnelles. Mon travail de thèse a eu pour objectif la compréhension de l'impact de ces deux niveaux de régulation sur la signalisation œstrogénique. Il a été récemment décrit que la sumoylation affectait de manière drastique l'activité du RE. La sumoylation est une modification dont le caractère réversible est assuré par des isopeptidases appelé SENPs (SENtrin Proteases). Dans une première étude nous avons montré que SENP2 pouvait fortement réprimer l'activité transcriptionnelle dépendante des œstrogènes ainsi que la prolifération cellulaire. Dans une seconde étude, nous nous sommes attelés à mieux caractériser les mécanismes d'action à l'origine du caractère répresseur du cofacteur transcriptionnel LCoR (Ligand-dependent Corepressor). Nous nous sommes plus précisément intéressés aux relations existant entre LCoR et un autre cofacteur du RE, RIP140 (Receptor Interacting Protein of 140 kDa) répresseur majeur de l'activité œstrogénique. Nous avons pu caractériser, outre les modes de recrutement des deux protéines, les modulations d'expression exercées par les deux cofacteurs. L'ensemble de nos travaux identifie de nouveaux cofacteurs des REs et contribue à une meilleure compréhension de la signalisation œstrogénique.Estrogens are involved in the proliferation of normal breast epithelial cells. The prolonged exposure to these hormones comes along with an increase of the risk of breast cancer.development. Estrogen receptors (ERs) mediate the effects of estrogens. The activity of these receptors is finely tuned by a large number of transcriptional cofactors, but also by post-translational modifications. This work aimed at understanding the impact of these regulations on estrogenic signalling. It was recently described that sumoylation could strongly affect ER-dependent activity. SUMO conjugation is a dynamic process which is reversed by SUMO specific proteases also known as SENtrin Proteases (SENPs). In a first study, we investigated the role of SENP2, in ER-dependent transcriptional activity. We showed that SENP2 could acts as a transcriptional cofactor independently of its catalytic activity by strongly repressing ER-dependent transcriptional activity. We also provided evidence for a role in in breast cancer cell line proliferation. In a second part of the work we investigated the mechanism of action of the transcriptional cofactor LCoR (Ligand-dependent Corepressor) with a specific emphasis on the relationship between LCoR and another ER cofactor, RIP140 (Receptor Interacting Protein of 140 kDa). We characterized a crossed expression modulation of the two transcription cofactors. We also depicted an interaction between these two corepressors and a regulation of LCoR activity by RIP140. Our work provides new insights in identifying new coregulators of ER and contributes to a better understanding of both LCoR and RIP140 mechanism of action, and therefore of estrogenic signalling.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Radiation TherapisTs Radiographer (RTTs) and risk management in radiotherapy: An international survey.

peer reviewed[en] PURPOSE: In order to study the role perception and the effective involvement of Radiation TherapisTs (RTTs) in risk management in radiotherapy, a survey was developed and distributed in five countries (France, Switzerland, Belgium, Ireland, the Netherlands). MATERIALS AND METHODS: The article presents the results of this survey and the comparison between the different countries. RESULTS: Overall, the results of the survey show a good involvement and perception of the RTTs around the risk management approach, although training in this area has yet to be systematized. CONCLUSION: Although with differences in the results between the participating countries, the survey seems to highlight the deployment of preventive actions that are evaluated as not very effective by the respondents and by the international scientific literature

Cdk2 strengthens the intra-S checkpoint and counteracts cell cycle exit induced by DNA damage

Although cyclin-dependent kinase 2 (Cdk2) controls the G1/S transition and promotes DNA replication, it is dispensable for cell cycle progression due to redundancy with Cdk1. Yet Cdk2 also has non-redundant functions that can be revealed in certain genetic backgrounds and it was reported to promote the G2/M DNA damage response checkpoint in TP53 (p53)-deficient cancer cells. However, in p53-proficient cells subjected to DNA damage, Cdk2 is inactivated by the CDK inhibitor p21. We therefore investigated whether Cdk2 differentially affects checkpoint responses in p53-proficient and deficient cell lines. We show that, independently of p53 status, Cdk2 stimulates the ATR/Chk1 pathway and is required for an efficient DNA replication checkpoint response. In contrast, Cdk2 is not required for a sustained DNA damage response and G2 arrest. Rather, eliminating Cdk2 delays S/G2 progression after DNA damage and accelerates appearance of early markers of cell cycle exit. Notably, Cdk2 knockdown leads to down-regulation of Cdk6, which we show is a non-redundant pRb kinase whose elimination compromises cell cycle progression. Our data reinforce the notion that Cdk2 is a key p21 target in the DNA damage response whose inactivation promotes exit from the cell cycle in G2

Transcriptional Repression of Estrogen Receptor α Signaling by SENP2 in Breast Cancer Cells.: ERα repression by SENP2

We wish to thank Drs Marc Piechaczyk and Guillaume Bossis for fruitful discussions. We are grateful to Dr Balaguer (IRCM, Montpellier) for providing ERE-β-globin-luciferase (EBL+), to Dr Khochbin (INSERM U823, Grenoble) for L8G5-luc and LexA-VP16, to Dr Chambon (IGBMC, Illkirch) for psg5-Erα, psg5-HE15, psg5-HEΔD and psg5-AF2, to Dr Dejean (Institut Pasteur, Paris) for pSG5-His-SUMO1, to Dr Hay (University of Dundee, Dundee) for pGEX-SUMO1 and to Dr Shuai (University of California, Los Angeles) for the pCMV-Flag PIAS1 expression vector.International audienceEstrogen receptors (ERs) are ligand-activated transcription factors involved in many physiological and pathological processes, including breast cancer. Their activity is fine-tuned by posttranslational modifications, notably sumoylation. In the present study, we investigated the role of the small ubiquitin-related modifier (SUMO) protease, SUMO1/sentrin/suppressor of Mif 2-specific peptidase 2 (SENP2), in the regulation of ERα activity. We first found SENP2 to significantly repress estradiol-induced transcriptional activity in breast cancer cells (MCF7 and T47D). This effect was observed with a reporter plasmid and on endogenous genes such as TFF1 and CTSD, which were shown to recruit SENP2 in chromatin immunoprecipitation experiments. Using glutathione S-transferase pull-down, coimmunoprecipitation and proximity ligation assays, SENP2 was found to interact with ERα and this interaction to be mediated by the amino-terminal region of the protease and the hinge region of the receptor. Interestingly, we demonstrated that ERα repression by SENP2 is independent of its SUMO protease activity and requires a transcriptional repressive domain located in the amino-terminal end of the protease. Using small interfering RNA assays, we evidenced that this domain recruits the histone deacetylase 3 (HDAC3), to be fully active. Furthermore, using both overexpression and knockdown strategies, we showed that SENP2 robustly represses estrogen-dependent and independent proliferation of MCF7 cells. We provided evidence that this effect requires both the proteolytic and transcriptional activities of SENP2. Altogether, our study unravels a new property for a SUMO protease and identifies SENP2 as a classical transcription coregulator