References of "Van de Weerdt, Cécile"
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See detailCrystallization of ornithine acetyltransferase from yeast by counter-diffusion and preliminary X-ray study
Maes, D.; Crabeel, M.; Van de Weerdt, Cécile ULg et al

in Acta Crystallographica Section F-Structural Biology and Crystallization Communications (2006), 62(Part 12), 1294-1297

A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes ... [more ▼]

A study is presented on the crystallization of ornithine acetyltransferase from yeast, which catalyzes the fifth step in microbial arginine synthesis. The use of the counter-diffusion technique removes the disorder present in one dimension in crystals grown by either the batch or hanging-drop techniques. This makes the difference between useless crystals and crystals that allow successful determination of the structure of the protein. The crystals belong to space group P4, with unit-cell parameters a = b = 66.98, c = 427.09 angstrom, and a data set was collected to 2.76 angstrom. [less ▲]

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See detailCounterdiffusion protein crystallisation in microgravity and its observation with PromISS (Protein Microscope for the International Space Station)
Zegers, Ingrid; Carotenuto, Luigi; Evrard, Christine ULg et al

in Microgravity Science and Technology (2006), XVIII

The crystallisation by counterdiffusion is a very efficient technique for obtaining high-quality protein crystals. A prerequisite for the use of counterdiffusion techniques is that mass transport must be ... [more ▼]

The crystallisation by counterdiffusion is a very efficient technique for obtaining high-quality protein crystals. A prerequisite for the use of counterdiffusion techniques is that mass transport must be controlled by diffusion alone. Sedimentation and convection can be avoided by either working in gelled systems, working in systems of small dimensions, or in the absence of gravity. We present the results from experiments performed on the ISS using the Protein Microscope for the International Space Station (PromISS), using digital holography to visualise crystal growth processes. We extensively characterised three model proteins for these experiments (cablys3*lysozyme, triose phosphate isomerase, and parvalbumin) and used these to assess the ISS as an environment for crystallisation by counterdiffusion. The possibility to visualise growth and movement of crystals in different types of experiments (capillary counterdiffusion and batch-type) is important, as movement of crystals is clearly not negligible. [less ▲]

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See detailEGF stimulates Pit-1 independent transcription of the human prolactin pituitary promoter in human breast cancer SK-BR-3 cells through its proximal AP-1 response element
Manfroid, Isabelle ULg; Van de Weerdt, Cécile ULg; Baudhuin, Ariane et al

in Molecular & Cellular Endocrinology (2005), 229(1-2), 127-39

Normal and neoplastic human mammary gland cells are targets for the proliferative action of prolactin. These cells also synthesize prolactin, thereby inducing an autocrine/paracrine proliferative loop. We ... [more ▼]

Normal and neoplastic human mammary gland cells are targets for the proliferative action of prolactin. These cells also synthesize prolactin, thereby inducing an autocrine/paracrine proliferative loop. We present the first extensive analysis of the transcriptional regulation of the human prolactin gene (hPRL) in human mammary tumor cells, SK-BR-3. We show that the pituitary promoter is functional in these cells in the absence of the pituitary-specific factor Pit-1. Expression of exogenous Pit-1 or epidermal growth factor (EGF) treatment stimulates the transfected hPRL pituitary promoter and the endogenous hPRL expression. EGF stimulation is mediated by increased synthesis of c-fos and c-jun, resulting in AP-1 binding to the proximal hPRL pituitary promoter. This regulation involves the EGF receptor, possibly ErbB2 that is highly expressed in SK-BR-3 cells, and a PI3K/JNK pathway. The stimulation of hPRL gene transcription by EGF in mammary cells may include hPRL in a complex regulatory network controlling growth of human mammary cells. [less ▲]

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See detailRecombinant human estrogen, androgen and progesterone receptors for detection of potential endocrine disruptors
Scippo, Marie-Louise ULg; Argiris, Catherine; Van de Weerdt, Cécile ULg et al

in Analytical and Bioanalytical Chemistry (2004), 378(3), 664-669

This work reports the binding capacity of various chemicals (so-called endocrine disruptors) to recombinant human steroid receptors (hERalpha, hPR and hAR). The tested chemicals are organochlorine ... [more ▼]

This work reports the binding capacity of various chemicals (so-called endocrine disruptors) to recombinant human steroid receptors (hERalpha, hPR and hAR). The tested chemicals are organochlorine insecticides (DDT and its metabolites, methoxychlor, aldrin, dieldrin, chlordecone, lindane, trichlorobenzene), estrogenic insecticides (endosulfan, toxaphene, nonachlor), herbicides (alachlor and atrazine), fungicides (benomyl and vinclozolin), industrial chemicals (nonylphenol, bisphenol A, diphenylphtalate), antioxidants (butylated hydroxyanisol) and some phytoestrogens. Except for phytoestrogens, most of the tested chemicals (DDT and its metabolites, aldrin, alpha- and beta-endosulfan, toxaphen, trans-nonachlor) show higher affinities for hPR than for hERalpha, indicating that the interaction with the progesterone receptor could contribute to the endocrine-disrupting effects imputed to these chemicals. We propose to use binding assays using recombinant human steroid receptors as screening tools for the detection of endocrine disruptors in various samples. [less ▲]

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See detailDe novo backbone and sequence design of an idealized alpha/beta-barrel protein: Evidence of stable tertiary structure
Offredi, Fabrice; Dubail, Fabien; Kischel, Philippe ULg et al

in Journal of Molecular Biology (2003), 325(1), 163-174

We have designed, synthesized, and characterized a 216 amino acid residue sequence encoding a putative idealized alpha/beta-barrel protein. The design was elaborated in two steps. First, the idealized ... [more ▼]

We have designed, synthesized, and characterized a 216 amino acid residue sequence encoding a putative idealized alpha/beta-barrel protein. The design was elaborated in two steps. First, the idealized backbone was defined with geometric parameters representing our target fold: a central eight parallel-stranded beta-sheet surrounded by eight parallel alpha-helices, connected together with short structural turns on both sides of the barrel. An automated sequence selection algorithm, based on the dead-end elimination theorem, was used to find the optimal amino acid sequence fitting the target structure. A synthetic gene coding for the designed sequence was constructed and the recombinant artificial protein was expressed in bacteria, purified and characterized. Far-UV CD spectra with prominent bands at 222nm and 208nm revealed the presence of alpha-helix secondary structures (50%) in fairly good agreement with the model. A pronounced absorption band in the near-UV CD region, arising from immobilized aromatic side-chains, showed that the artificial protein is folded in solution. Chemical unfolding monitored by tryptophan fluorescence revealed a conformational stability (DeltaG(H2O)) of 35kJ/mol. Thermal unfolding monitored by near-UV CD revealed a cooperative transition with an apparent T(m) of 65 degrees C. Moreover, the artificial protein did not exhibit any affinity for the hydrophobic fluorescent probe 1-anilinonaphthalene-8-sulfonic acid (ANS), providing additional evidence that the artificial barrel is not in the molten globule state, contrary to previously designed artificial alpha/beta-barrels. Finally, 1H NMR spectra of the folded and unfolded proteins provided evidence for specific interactions in the folded protein. Taken together, the results indicate that the de novo designed alpha/beta-barrel protein adopts a stable three-dimensional structure in solution. These encouraging results show that de novo design of an idealized protein structure of more than 200 amino acid residues is now possible, from construction of a particular backbone conformation to determination of an amino acid sequence with an automated sequence selection algorithm. [less ▲]

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See detailTranscription of the human prolactin gene in mammary cells
Baudhuin, A.; Manfroid, Isabelle ULg; Van de Weerdt, Cécile ULg et al

in Annals of the New York Academy of Sciences (2002), 973

Expression of human prolactin in the Mammary gland, one of the main target organs of this hormone, leads to the formation of an autocrine-paracrine proliferative loop in this tissue. Involvement of ... [more ▼]

Expression of human prolactin in the Mammary gland, one of the main target organs of this hormone, leads to the formation of an autocrine-paracrine proliferative loop in this tissue. Involvement of prolactin in normal and neoplastic mammary development triggered the interest in transcriptional regulation of the human prolactin gene in mammary cells. Analysis of this regulation, and comparison to that in the pituitary, will contribute to a better understanding of mammary gland development and tumor formation. Here we present the first extensive analysis of the transcriptional regulation of the human prolactin gene in human mammary tumor cells. [less ▲]

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See detailDetection of illegal growth promoters in biological samples using receptor binding assays
Scippo, Marie-Louise ULg; Van de Weerdt, Cécile ULg; Willemsen, Philippe et al

in Analytica Chimica Acta (2002), 473(1-2), 135-141

In the European Union (EU), the use of growth-promoting substances in meat production is banned. The control of growth promoters, especially steroid hormones, is presently based on expensive and time ... [more ▼]

In the European Union (EU), the use of growth-promoting substances in meat production is banned. The control of growth promoters, especially steroid hormones, is presently based on expensive and time-consuming chromatographic methods of analysis or, sometimes, for screening purposes, on radio- or enzyme-immunoassays, all of which are often too specific to allow effective multi-analyte control. In order to develop rapid and inexpensive multi-analyte detection tests, we proposed the use of hormonal receptors as detection tools. The system described here (radio-receptor assays) is based on a direct bindin g assay of steroid hormones to their respective receptors. Human receptors to estrogens (hERalpha), androgens (hAR), progestagens (hPR) and glucocorticoids (hGR) have been produced by genetic engineering in bacteria or in eucaryotic cells. Binding analyses revealed that the obtained receptor proteins retained a high affinity for their corresponding native ligand. In addition, competition studies continued that each of the four receptors displays a specificity profile for a series of analogs in agreement with the literature. Finally, the stability of these recombinant receptors is sufficient to allow their use in test kits. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailFar upstream sequences regulate the human prolactin promoter transcription
Van de Weerdt, Cécile ULg; Peers, Bernard ULg; Belayew, A. et al

in Neuroendocrinology (2000), 71(2), 124-37

The human prolactin gene is mainly expressed in pituitary lactotrope cells, but transcription from an alternative, far upstream promoter was detected in lymphoid, placental and mammary cells. We describe ... [more ▼]

The human prolactin gene is mainly expressed in pituitary lactotrope cells, but transcription from an alternative, far upstream promoter was detected in lymphoid, placental and mammary cells. We describe the transcriptional activity in rat pituitary cells of the complete region separating the two promoters, using transient transfection experiments. A far upstream activating region was only functional in combination with the prolactin promoter. DNaseI protection experiments revealed, in addition to binding sites for the pituitary-specific factor Pit-1, sites (e.g. SD1) for several ubiquitous factors and one lymphoid-specific factor (SD4). A single copy of the ubiquitous site SD1 or the lymphoid-specific site SD4 was unable to activate transcription of a heterologous promoter in pituitary cells. However, SD1 activated transcription in nonpituitary cells and SD4 was functional specifically in lymphoid cells. Five copies of a distal site (D8) activated transcription in each cell type tested. Gel retardation experiments show that this site binds the specific factor C/EBP in liver and a distinct factor in other cell types. Our results suggest that different elements within this large region direct specific expression from each promoter via a complex interplay between cell-specific and ubiquitous transcription factors. [less ▲]

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See detailRégulation transcriptionnelle du gène de la prolactine humaine
Muller, Marc ULg; Berwaer, Monique; Caccavelli, Laure et al

in Medecine Sciences : M/S (1998), 14(580-587),

Le gène humain de la prolactine (hPRL) est exprimé essentiellement par l'antéhypophyse. L'analyse des éléments régulateurs de la transcription sur plus de 5 000 bases en amont du site de début de ... [more ▼]

Le gène humain de la prolactine (hPRL) est exprimé essentiellement par l'antéhypophyse. L'analyse des éléments régulateurs de la transcription sur plus de 5 000 bases en amont du site de début de transcription a montré l'importance du contrôle par le facteur de transcription Pit-1, spécifique de l'hypophyse, à côté de facteurs ubiquistes. Des hormones modulent l'expression du gène hPRL, transmettant leur signal par les voies intracellulaires de l'AMP cyclique et du calcium, relayées au niveau du promoteur proximal (-250/+1) essentiellement par les facteurs de transcription Pit-1 et AP-1. Les récepteurs nucléaires contrôlent aussi en partie la transcription de hPRL: le récepteur des oestrogènes l'active en se liant aux éléments de réponse distaux ; les récepteurs nucléaires des hormones thyroïdiennes et des glucocorticoïdes la répriment en interférant respectivement avec la fonction activatrice de AP-1 et de Pit-1. [less ▲]

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See detailThyroid hormone inhibits the human prolactin gene promoter by interfering with activating protein-1 and estrogen stimulations
Pernasetti, Flavia; Caccavelli, L.; Van de Weerdt, Cécile ULg et al

in Molecular Endocrinology (Baltimore, Md.) (1997), 11(7), 986-96

Transcription of the human PRL (hPRL) gene in the pituitary is subject to tissue-specific and multihormonal regulation involving two main regulatory regions, a proximal promoter and a distal enhancer. In ... [more ▼]

Transcription of the human PRL (hPRL) gene in the pituitary is subject to tissue-specific and multihormonal regulation involving two main regulatory regions, a proximal promoter and a distal enhancer. In this report we show that thyroid hormone inhibits the expression of the hPRL gene in rat pituitary cells. Transient expression experiments show that thyroid hormone regulation involves a strong inhibitory element, located in the proximal (-164/-35) promoter, which is modulated by a more distal stimulatory response control region. Gel retardation experiments reveal that the thyroid hormone receptor does not bind to the proximal negative element. We show the existence of an activating protein-1 (AP-1) response element located at positions -61 to -54 of the proximal promoter, conferring AP-1 stimulation to the hPRL promoter. This AP-1 induction is abolished when hormone-bound thyroid hormone receptor is present, indicating that there is an interference between the thyroid hormone receptor and AP-1 regulatory pathways. Furthermore, using the complete hPRL upstream region, we show that estrogen induction is abolished by simultaneous thyroid hormone treatment. [less ▲]

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