References of "Muller, Marc"
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See detailEffects of polycyclic aromatic hydrocarbons on hepatic steroid metabolism
Brasseur, Catherine ULg; Muller, Marc ULg; Widart, Stéphane et al

in Journal of Biotechnology (2007), 131(2, Suppl. S), 73

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See detailSet up of an experimental tool in order to investigate food chemical contaminant toxicity at realistic concentrations
Ribonnet, Laurence; Sergent, Thérèse; Nobels, Ingrid et al

in Toxicology Letters (2007), 172

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See detailTranscriptional regulation of the mouse doublecortin gene in differentiating neurons
Plumier, Jean-Christophe ULg; Muller, Marc ULg; Rogister, Bernard ULg et al

in International Journal of Developmental Neuroscience (2006, December), 24(8), 535

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See detailCloning of the prepro C-RFa gene and brain localization of the active peptide in Salmo salar
Montefusco-Siegmund, R. A.; Romero, A.; Kausel, G. et al

in Cell & Tissue Research (2006), 325(2), 277-285

In all vertebrates, the synthesis and release of prolactin (Prl) from pituitary lactotroph cells is tightly controlled by hypothalamic factors. We have cloned and characterized a hypothalamic cDNA from ... [more ▼]

In all vertebrates, the synthesis and release of prolactin (Prl) from pituitary lactotroph cells is tightly controlled by hypothalamic factors. We have cloned and characterized a hypothalamic cDNA from Atlantic salmon (Salmo salar) encoding C-RFa, a peptide structurally related to mammalian Prl-releasing peptide (PrRP). The deduced preprohormone precursor is composed of 155 amino acid residues presenting a 87.1% similarity to chum salmon C-RFa and a 100% similarity to all fish C-RFa in the bioactive precursor motifs. C-RFa-immunoreactive perikarya and fibres were located in the brain of S. salar, especially in the hypothalamus, olfactory tract, optic tectum and cerebellum. In contrast, immunolabelled fibres were not observed in the pituitary stalk or in the hypophysis. However, interestingly, we detected immunolabelled cells in the rostral pars distalis of the pituitary in the basolateral region in which Prl is synthesized. These results were confirmed by obtaining a strong signal by using reverse transcription/polymerase chain reaction (RTPCR) on mRNA from both hypothalamus and pituitary. These data show, for the first time, by immunohistochemistry and RT-PCR, that C-RFa is produced in pituitary cells. Finally, based on these results, a possible function for CRFa as a locally produced PrRP in this teleost is discussed. [less ▲]

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See detailIdentification of novel prolactin releasing peptide receptors of Cyprinus carpio and Salmo salar expressed in the pituitary gland
Romero, A. P.; Montefusco, R.; Lopez, Mauricio et al

in Journal of Experimental Zoology. Part A, Comparative Experimental Biology (2006, February 01), 305A(2), 171

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See detailExpression of the somatolactin beta gene during zebrafish embryonic development
Lopez, Mauricio; Nica, G.; Motte, Patrick ULg et al

in Gene Expression Patterns (2006), 6(2), 156-161

Somatolactin (Sl) is a pituitary hormone closely related to prolactin (Prl) and growth hormone that was until now only found in various fish species. We isolated the cDNA coding for zebrafish Sl beta and ... [more ▼]

Somatolactin (Sl) is a pituitary hormone closely related to prolactin (Prl) and growth hormone that was until now only found in various fish species. We isolated the cDNA coding for zebrafish Sl beta and we identified the gene encoding this hormone. We also obtained a 1 kb genomic fragment corresponding to the sl beta upstream promoter region. Furthermore, the sl beta expression pattern was examined during zebrafish embryogenesis using whole-mount in situ hybridization. Sl beta mRNA is first detected in a single cell at the anterior border of the neural plate starting at 23 h post fertilization (hpf). Sl beta-expressing cells also express the transcription factor pit1 and are located close to prl-expressing cells. Using combined fluorescent in situ hybridization, we show that sl beta- and prl-expressing cells are clearly distinct at 29 hpf. Starting at 30 hpf, the number of sl beta positive cells increases and their location becomes more clearly distinct from lactotrope cells, in a more posterior position. At later stages (48 hpf), sl beta expression was observed posterior to growth hormone expression, again in a distinct cell type. We show that zebrafish mutants aal, as well as mutants in the pit1 gene, are deficient in sl beta expression. In conclusion, sl beta expression defines a new, additional cell type in zebrafish pituitary that depends on pit1 and aal for its differentiation. (C) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailModular changes of cis-regulatory elements from two functional Pit1 genes in the duplicated genome of Cyprinus carpio.
Kausel, G.; Salazar, M.; Castro, L. et al

in Journal of Cellular Biochemistry (2006), 99(3), 905-21

The pituitary-specific transcription factor Pit1 is involved in its own regulation and in a network of transcriptional regulation of hypothalamo-hypophyseal factors including prolactin (PRL) and growth ... [more ▼]

The pituitary-specific transcription factor Pit1 is involved in its own regulation and in a network of transcriptional regulation of hypothalamo-hypophyseal factors including prolactin (PRL) and growth hormone (GH). In the ectotherm teleost Cyprinus carpio, Pit1 plays an important role in regulation of the adaptive response to seasonal environmental changes. Two Pit1 genes exist in carp, a tetraploid vertebrate and transcripts of both genes were detected by RT-PCR analysis. Powerful comparative analyses of the 5'-flanking regions revealed copy specific changes comprising modular functional units in the naturally evolved promoters. These include the precise replacement of four nucleotides around the transcription start site embedded in completely conserved regions extending upstream of the TATA-box, an additional transcription factor binding site in the 5'-UTR of gene-I and, instead, duplication of a 9 bp element in gene-II. Binding of nuclear factors was assessed by electro mobility shift assays using extracts from rat pituitary cells and carp pituitary. Binding was confirmed at one conserved Pit1, one conserved CREB and one consensus MTF1. Interestingly, two functional Pit1 sites and one putative MTF1 binding site are unique to the Pit1 gene-I. In situ hybridization experiments revealed that the expression of gene-I in winter carp was significantly stronger than that of gene-II. Our data suggest that the specific control elements identified in the proximal regulatory region are physiologically relevant for the function of the duplicated Pit1 genes in carp and highlight modular changes in the architecture of two Pit1 genes that evolved for at least 12 MYA in the same organism. [less ▲]

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See detailTranscriptional regulation of the mouse doublecortin gene in differentiating neurons
Plumier, Jean-Christophe ULg; Muller, Marc ULg; Rogister, Bernard ULg et al

in International Journal of Developmental Neuroscience (2006), 24

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See detailExpression and functional properties of four slow skeletal troponin T isoforms in rat muscles
Kischel, Philippe ULg; Bastide, Bruno; Muller, Marc ULg et al

in American Journal of Physiology - Cell Physiology (2005), 289(2), 437-443

We investigated the expression and functional properties of slow skeletal troponin T(sTnT) isoforms in rat skeletal muscles. Four sTnT cDNAs were cloned from the slow soleus muscle. Three isoforms were ... [more ▼]

We investigated the expression and functional properties of slow skeletal troponin T(sTnT) isoforms in rat skeletal muscles. Four sTnT cDNAs were cloned from the slow soleus muscle. Three isoforms were found to be similar to sTnT1, sTnT2, and sTnT3 isoforms described in mouse muscles. A new rat isoform, with a molecular weight slightly higher than that of sTnT3, was discovered. This fourth isoform had never been detected previously in any skeletal muscle and was therefore called sTnTx. From both expression pattern and functional measurements, it appears that sTnT isoforms can be separated into two classes, high-molecular-weight ( sTnT1, sTnT2) and low-molecular-weight ( sTnTx, sTnT3) isoforms. By comparison to the apparent migration pattern of the four recombinant sTnT isoforms, the newly described low-molecular-weight sTnTx isoform appeared predominantly and typically expressed in fast skeletal muscles, whereas the higher-molecular-weight isoforms were more abundant in slow soleus muscle. The relative proportion of the sTnT isoforms in the soleus was not modified after exposure to hindlimb unloading (HU), known to induce a functional atrophy and a slow-to-fast isoform transition of several myofibrillar proteins. Functional data gathered from replacement of endogenous troponin complexes in skinned muscle fibers showed that the sTnT isoforms modified the Ca2+ activation characteristics of single skeletal muscle fibers, with sTnT2 and sTnT1 conferring a similar increase in Ca2+ affinity higher than that caused by low-molecular-weight isoforms sTnTx and sTnT3. Thus we show for the first time the presence of sTnT in fast muscle fibers, and our data show that the changes in neuromuscular activity on HU are insufficient to alter the sTnT expression pattern. [less ▲]

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See detailIdentification of cis-regulatory elements controlling two differentially expressed Pit-1 genes in the duplicated genome of Cyprinus carpio
Kausel, G. M.; Castro, L. A.; Vera, T. S. et al

in FEBS Journal (2005, July), 272(Suppl. 1), 469-470

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See detailTranscritional regulation of the mouse doublecortin gene in differentiating neurons
Piens, Marie; Muller, Marc ULg; Lion, Michelle et al

Poster (2005)

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See detailAnalysis of the mouse doublecortin gene promoter in neurons
Piens, Marie; Muller, Marc ULg; Lion, Michelle ULg et al

Poster (2005)

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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 detailEnhancement of steroid receptor-mediated transcription for the development of highly responsive bioassays
Willemsen, Philippe; Scippo, Marie-Louise ULg; Maghuin-Rogister, Guy ULg et al

in Analytical and Bioanalytical Chemistry (2005), 382(4), 894-905

We have previously generated several transformed human mammary cell lines for the detection of steroid receptor-mediated activities and used these cell lines to detect and characterize steroid hormone ... [more ▼]

We have previously generated several transformed human mammary cell lines for the detection of steroid receptor-mediated activities and used these cell lines to detect and characterize steroid hormone (ant)agonistic compounds. In this report, we describe the specific optimization procedures used to enhance receptor-mediated transcription through the human glucocorticoid, progesterone and androgen receptors, respectively. Sodium arsenite-induced chemical stress leads to a substantial and specific increase in the glucocorticold receptor-mediated transcription, resulting in maximal stimulations of more than 2000-fold by the agonist dexamethasone. Similarly, a combined treatment with forskolin (an activator of adenylate cyclase) and trichostatin A (an inhibitor of histone deacetylases) leads to a synergistic enhancement of progesterone or androgen stimulation, resulting in a maximal induction of more than 200-fold or about 100-fold, respectively. The enhanced responses to specific steroids are mediated by the corresponding nuclear receptor. We show that by using these enhanced transcriptional stimulation protocols, it is possible to detect lower amounts of steroid hormones without substantially affecting the relative biological activities of various agonists. Finally, the application of these enhanced reporter cell assays to real biological samples from meat-producing animals is evaluated, and some validation parameters are presented. [less ▲]

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See detailUse of reporter cell lines for detection of endocrine-disrupter activity
Willemsen, Philippe; Scippo, Marie-Louise ULg; Kausel, G. et al

in Analytical and Bioanalytical Chemistry (2004), 378(3), 655-663

We have studied stable transformed human mammary cell lines with highly inducible steroid receptor-mediated luciferase reporter gene expression. Cells responding specifically to glucocorticoids ... [more ▼]

We have studied stable transformed human mammary cell lines with highly inducible steroid receptor-mediated luciferase reporter gene expression. Cells responding specifically to glucocorticoids, progestagens, androgens, or estrogens are described and characterized. The use of this high-throughput, cell-based assay for analysis of steroid (ant)agonists is reported. Systematic characterization of endocrine-disrupting activity on human receptors and in a human-cell system is interpreted for a selection of xenobiotics. We show that the phytoestrogens apigenin and genistin have progestagenic and androgenic activity, respectively. Finally, application of cell-based assays to the analysis of environmental samples is discussed. [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 detailReceptor-based screening assays: New perspectives in anti-doping control
Scippo, Marie-Louise ULg; Willemsen, Philippe; Danyi, Sophie ULg et al

in Chromatographia (2004), 59(Suppl. S), 23-27

The so-called "growth promoters", steroid hormones and beta-agonists, are currently controlled by using hyphenated analytical methods (chromatography coupled to mass spectrometry) or, sometimes for ... [more ▼]

The so-called "growth promoters", steroid hormones and beta-agonists, are currently controlled by using hyphenated analytical methods (chromatography coupled to mass spectrometry) or, sometimes for screening purposes, on immunoassays. These methods are often too specific to allow an effective multianalyte control. To develop more efficient assays, the use of hormonal receptors as detection tools (receptor-based binding assays and cell-based assays) is proposed. Receptor-based assays represent useful tools in screening of hormonal residues in food, but they could also be applied in doping control (to detect "new" hormonal substances). Furthermore, these assays could be used to monitor the human exposure to endocrine disruptors. [less ▲]

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See detailPitx factors are involved in basal and hormone-regulated activity of the human prolactin promoter
Quentien, M. H.; Manfroid, Isabelle ULg; Moncet, D. et al

in Journal of Biological Chemistry (2002), 277(46), 44408-44416

The pituitary-specific POU homeodomain factor Pit-1 likely interacts with other factors for cell-specific expression of prolactin. Here we identify the paired-like homeobox transcription factors Pitx1 and ... [more ▼]

The pituitary-specific POU homeodomain factor Pit-1 likely interacts with other factors for cell-specific expression of prolactin. Here we identify the paired-like homeobox transcription factors Pitx1 and Pitx2 as factors functionally activating the proximal human prolactin promoter (hPRL-164luc). Using in vitro binding assays and a series of site-specific mutations of the proximal hPRL promoter, we mapped the 131 and B2 bicoid sites involved in Pitx-mediated transactivation of the hPRL-164luc construct. In somatolactotroph GH4C1 cells, basal proximal hPRL promoter activity was inhibited by a Pitx2 dominant-negative form in a dose-dependent manner, whereas binding disruptive mutations in the Pitx sites significantly reduced basal activity of the promoter. We also show that synergistic activation of hPRL-164luc by Pitx2 and Pit-1 requires the integrity of the B2 Pitx binding site, and at least one of the P1 and P2 Pit-1 response elements. In addition, mutation in the B2 Pitx site results in attenuation of the promoter's responsiveness to forskolin, thyrotropin-releasing hormone, and epidermal growth factor. Conversely, Pitx1 or Pitx2 overexpression in GH4C1 cells leads to an enhancement of the drugs stimulatory effects. Altogether, these results suggest that full responsiveness to several signaling pathways regulating the hPRL promoter requires the B2 Pitx binding site and that Pitx factors may be part of the proteic complex involved in these regulations. Finally, in situ hybridization analysis showing coexpression of the PRL and Pitx2 genes in rat and human lactotroph cells corroborates the physiological relevance of these results. [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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