References of "Manfroid, Isabelle"
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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 detailInhibition of protein phosphatase PP1 in GH3B6, but not in GH3 cells, activates the MEK/ERK/c-fos pathway and the human prolactin promoter, involving the coactivator CPB/p300
Manfroid, Isabelle ULg; Martial, Joseph ULg; Muller, Marc ULg

in Molecular Endocrinology (Baltimore, Md.) (2001), 15(4), 625-37

The human (hPRL) PRL gene proximal promoter (-164/+15) is the target for numerous signal transduction pathways involving protein kinases. The inhibitor of Ser/Thr-protein phosphatases okadaic acid (OA ... [more ▼]

The human (hPRL) PRL gene proximal promoter (-164/+15) is the target for numerous signal transduction pathways involving protein kinases. The inhibitor of Ser/Thr-protein phosphatases okadaic acid (OA) was shown to induce this promoter in rat pituitary GH3B6 through a synergism between increased amounts of the ubiquitous factor AP-1 and the pituitary-specific factor Pit-1. Here we show that this activation results mainly from transcriptional stimulation of the c-fos promoter leading to increased AP-1 activity. We report the surprising absence of the hPRL and c-fos promoter stimulation by OA in GH3 cells, closely related to GH3B6 cells, and we use this discrepancy to dissect the precise mechanism of action. c-fos gene activation involves the mitogen-activated kinase (MAPK)-ternary complex factor (TCF) pathway and can be obtained by expressing active V12ras in both cell lines. We show that OA acts by inhibiting protein phosphatase PP1, thereby protecting MAPK kinase (MEK)1/2 and/or a MEK1/2-kinase from dephosphorylation. PP1 inhibition of MEK activation by V12ras does not occur in GH3 cells, indicating that a distinct, PP1-sensitive phosphorylation site is used in GH3B6 cells to activate the TCF pathway in GH3B6 cells. Finally, we show that the synergistic OA activation of the hPRL promoter by Pit-1 and AP-1 is independent of the Pit-1 transactivation domain and is mediated by the general coactivator (CRE-binding protein)-binding protein (CBP)/p300. [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 detailTranscription factor AP1 is involved in basal and okadaic acid-stimulated activity of the human PRL promoter
Caccavelli, Laure; Manfroid, Isabelle ULg; Martial, Joseph ULg et al

in Molecular Endocrinology (Baltimore, Md.) (1998), 12(8), 1215-27

The tumor promoter, okadaic acid (OA), an inhibitor of protein phosphatases, stimulates the activity of the human PRL (hPRL) proximal promoter. We analyzed in detail the effects of OA on transcription ... [more ▼]

The tumor promoter, okadaic acid (OA), an inhibitor of protein phosphatases, stimulates the activity of the human PRL (hPRL) proximal promoter. We analyzed in detail the effects of OA on transcription factor binding to elements P1 and P2 of this promoter, sequences known to contain at least one Pit-1 binding site each. OA treatment induces binding of an AP1-related transcription factor to the P1 site. This effect is specific, as protein binding to the P2 site is not altered by the treatment. Specific antibodies were used to confirm that the OA-induced complex is related to AP1 and to show that it contains JunD and c-fos, but not Pit-1. The increase in AP1 binding to P1 and to a canonical AP1 site correlates to an increase in cellular JunD and c-fos content. Transient transfection experiments showed that both AP1 and Pit-1 are involved in the regulation of basal and OA-stimulated promoter activity. Our results demonstrate that a member of the AP1 family, containing JunD and c-fos, can bind to the proximal element P1 within the hPRL promoter. In addition, they show that AP1 is involved in both basal and OA-stimulated expression of the hPRL gene. [less ▲]

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See detailIdentification and modulation of a growth hormone-binding protein in rainbow trout (Oncorhynchus mykiss) plasma during seawater adaptation.
Sohm, F.; Manfroid, Isabelle ULg; Pezet, A. et al

in General and Comparative Endocrinology (1998), 111(2), 216-24

A soluble protein that specifically bound 125I-human growth hormone (hGH) was identified in rainbow trout plasma, using HPLC-gel filtration. The binding affinity of the protein for hGH was 1.2 x 10(9)M-1 ... [more ▼]

A soluble protein that specifically bound 125I-human growth hormone (hGH) was identified in rainbow trout plasma, using HPLC-gel filtration. The binding affinity of the protein for hGH was 1.2 x 10(9)M-1. 125I-rainbow trout GH (tGH) was also able to bind to the protein albeit with a lower affinity (6.6 x 10(7)M-1) than hGH. Crosslinking experiments using 125I-hGH revealed two specific bands of 150 and 130 kDa. The complex 125I-hGH-BP could be precipitated by a monoclonal anti-GH receptor antibody, suggesting a close relationship between the plasma GH-BP and the GH receptor. A fourfold increase in the hGH binding to the GH-BP was shown 48 h after transfer of the fishes from freshwater to seawater. The increase in binding was related to a high binding capacity without significant changes in binding affinity. These results suggest a potential role of this related GH-BP as an index of GH effects during seawater adaptation in salmonids. [less ▲]

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