Rôle de l'irradiation de la chaîne mammaire interne après mastectomie dans le cancer du sein

CAEN-BU Médecine pharmacie (141182102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

A Unified French/English Syllabic Model for Handwriting Recognition

International audienceIn this paper we introduce a new unified syllabic model for French and English handwriting recognition, based on hidden Markov models (HMM). The recognition system training and recognition components such as optical models, lexicons and language models are designed to be language independent. In this purpose a syllable based model is proposed for French and English. This model is evaluated and compared to n-gram character and words models. A promising performance is achieved by the syllabic model, which meets the words model performance, with the advantage of a reduced system complexity. Furthermore, the unification of likely similar scripts improves the system performance over all models considering the English and French languages. The French RIMES and the English IAM datasets are used for the evaluation

Change detection for road condition mapping based on dry and rainy season VHR dual-pol radar imagery over tropical areas. Application to Chad

International audienceNew Very High Resolution dual-polarization radar sensors in X-band (TerraSAR-X and Cosmo-Skymed) are offering technical opportunities for the detection of road condition changes between dry and rainy period in tropical areas. We applied classification methods (fuzzy logic and learning algorithms), multi-incidence and optical-radar combination in order to estimate surface elements (relief, flooded areas), soil properties (wetness, surface roughness) and road conditions from multi-date acquisitions over SW Chad. These estimations are calibrated with data measurements on the field. They are included in a road condition service designed for military, humanitarian and industrial logistics

Dynamic and selective interactions of the transcriptional corepressor TIF1 beta with the heterochromatin protein HP1 isotypes during cell differentiation.

Cell differentiation is a multi-step process marked by progressive silencing of gene expression through mechanisms believed to involve heterochromatin. We have previously shown that interaction between the Kr?l associated box-containing zinc finger proteins (KRAB-ZFP) corepressor TIF1beta and the heterochromatin proteins HP1 is essential for progression through differentiation of embryonal carcinoma F9 cells. This analysis clearly demonstrated the link between gene specific repressors, components of heterochromatin and cell differentiation. In mammals, there are three HP1 isotypes, HP1alpha, beta, and gamma, that appear to be involved in both eu- and heterochromatin, but whose individual functions are still poorly defined. Therefore, the aim of the present study was to determine in vivo (i) which HP1 isotypes interact with TIF1beta, (ii) in which sub-nuclear compartments these interactions occur and (iii) whether these interactions are regulated during cell differentiation. To address these questions, we established stable F9 cell lines co-expressing TIF1beta fused to the ECFP fluorophore and HP1alpha, beta, or gamma fused to the EYFP fluorophore. Using the F?r resonance energy transfer (FRET) technology, we map the physical interaction between TIF1beta-CFP and the different HP1-YFP isotypes in living F9 cells. We demonstrate that in non-differentiated cells, TIF1beta-CFP/HP1-YFP interaction occurs only within euchromatin and involves selectively HP1beta-YFP and HP1gamma-YFP, but not HP1alpha-YFP. Furthermore, in differentiated cells, TIF1beta-CFP selectively associates with HP1beta-YFP within heterochromatin, while TIF1beta-CFP/HP1gamma-YFP is exclusively present within euchromatin. No physical TIF1beta-CFP/HP1alpha-YFP interaction is detected in neither non differentiated nor differentiated cells. These results support the notion that, in vivo, HP1 isotypes have specific nonredundant functions and provide evidence for HP1beta playing an essential role in the shuttling of TIF1beta from eu- to heterochromatin during cell differentiation

Association of the transcriptional corepressor TIF1β with heterochromatin protein 1 (HP1): an essential role for progression through differentiation

The transcriptional intermediary factor 1β (TIF1β) is a corepressor for KRAB-domain-containing zinc finger proteins and is believed to play essential roles in cell physiology by regulating chromatin organization at specific loci through association with chromatin remodeling and histone-modifying activities and recruitment of heterochromatin protein 1 (HP1) proteins. In this study, we have engineered a modified embryonal carcinoma F9 cell line (TIF1β(HP1box/-)) expressing a mutated TIF1β protein (TIF1β(HP1box)) unable to interact with HP1 proteins. Phenotypic analysis of TIF1β(HP1box/-) and TIF1β(+/-) cells shows that TIF1β–HP1 interaction is not required for differentiation of F9 cells into primitive endoderm-like (PrE) cells on retinoic acid (RA) treatment but is essential for further differentiation into parietal endoderm-like (PE) cells on addition of cAMP and for differentiation into visceral endoderm-like cells on treatment of vesicles with RA. Complementation experiments reveal that TIF1β–HP1 interaction is essential only during a short window of time within early differentiating PrE cells to establish a selective transmittable competence to terminally differentiate on further cAMP inducing signal. Moreover, the expression of three endoderm-specific genes, GATA6, HNF4, and Dab2, is down-regulated in TIF1β(HP1box/-) cells compared with wild-type cells during PrE differentiation. Collectively, these data demonstrate that the interaction between TIF1β and HP1 proteins is essential for progression through differentiation by regulating the expression of endoderm differentiation master players

Selective interaction between the chromatin-remodeling factor BRG1 and the heterochromatin-associated protein HP1α

Mammalian heterochromatin protein 1 (HP1) α, HP1β and HP1γ are closely related non-histone chromosomal proteins that function in gene silencing, presumably by organizing higher order chromatin structures. Here, we show by co-immunoprecipitation that HP1α, but neither HP1β nor HP1γ, forms a complex with the BRG1 chromatin-remodeling factor in HeLa cells. In vitro, BRG1 interacts directly and preferentially with HP1α. The region conferring this preferential binding has been mapped to residues 106–180 of the HP1α C-terminal chromoshadow domain. Using site-directed mutagenesis, we have identified three amino acid residues I113, A114 and C133 in HP1α (K, P and S in HP1β and HP1γ) that are essential for the selective interaction of HP1α with BRG1. Interestingly, these residues were also shown to be critical for the silencing activity of HP1α. Taken together, these results demonstrate that mammalian HP1 proteins are biochemically distinct and suggest an entirely novel function for BRG1 in modulating HP1α-containing heterochromatic structures

TIF1delta, a novel HP1-interacting member of the transcriptional intermediary factor 1 (TIF1) family expressed by elongating spermatids

TIF1 (transcriptional intermediary factor 1) proteins are encoded by an expanding family of developmental and physiological control genes that are conserved from flies to man. These proteins are characterized by an N-terminal RING-B box-coiled-coil (RBCC) motif and a C-terminal PHD finger/bromodomain unit, and have been implicated in epigenetic mechanisms of transcriptional repression involving histone modifiers and heterochromatin-binding proteins. We describe here the isolation and functional characterization of a fourth murine TIF1 gene, TIF1delta. The predicted TIF1delta protein displays all the structural hallmarks of a bona fide TIF1 family member and resembles the other TIF1s in that it can exert a deacetylase-dependent silencing effect when tethered to a promoter region. Moreover, like TIF1alpha and TIF1beta, TIF1delta can homodimerize and contains a PXVXL motif necessary and sufficient for HP1 (heterochromatin protein 1) binding. Although TIF1alpha and TIF1beta also bind nuclear receptors and Kruppel-associated boxes specifically and respectively, TIF1delta appears to lack nuclear receptor- and Kruppel-associated box binding activity. Furthermore, TIF1delta is unique among the TIF1 family proteins in that its expression is largely restricted to the testis and confined to haploid elongating spermatids, where it associates preferentially with HP1 isotype gamma (HP1gamma) and forms discrete foci dispersed within the centromeric chromocenter and the surrounding nucleoplasm. Collectively, these data are consistent with specific, nonredundant functions for the TIF1 family members in vivo and suggest a role for TIF1delta in heterochromatin-mediated gene silencing during postmeiotic phases of spermatogenesis