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In the present study, we analyzed the influence of retinoic acids on the expression of alpha-1 acid glycoprotein (AGP). We show that in rat primary hepatocytes, 9-cis retinoic acid and all-trans retinoic acid increase AGP gene expression at the transcriptional level. Transient transfections of rat primary hepatocytes with a reporter construct driven by the rat AGP gene promoter indicated that retinoids regulate AGP gene expression via the -763/-138 region of the AGP promoter. Furthermore, cotransfection experiments with retinoic acid receptor alpha (RARalpha) and retinoid X receptor alpha (RXRalpha) expression vectors in NIH3T3 cells demonstrated that both RXRalpha/RXRalpha homodimer and RXRalpha/RARalpha heterodimer are competent for ligand-induced transactivation of the AGP promoter. Unilateral deletion and site-directed mutagenesis identified two retinoic-acid responsive elements (RARE), RARE-I and RARE-II, which interestingly correspond to a direct repeat of two TGACCT-related hexanucleotides separated by a single bp only (DR1-type response element). Cotransfection assays showed that RXRalpha and RARalpha activate AGP gene transcription through these two elements either as a homodimer (RXRalpha/RXRalpha) or as a heterodimer (RXRalpha/RARalpha). The RXRalpha/RXRalpha homodimer acts most efficiently through the RARE-I response element to promote AGP transactivation, whereas the RXRalpha/RARalpha heterodimer mediates transactivation better via the RARE-II responsive element.

Resume Lˈaugmentation de lˈhCG observee dans le serum maternel au second trimestre en cas de trisomie 21 fœtale est encore peu documentee. Elle resulte dˈune immaturite placentaire affectant la differenciation du cytotrophoblaste en syncytiotrophoblaste, tissu endocrine du placenta. Le niveau de production de lˈhCG resterait au second trimestre aussi eleve quˈau premier trimestre. Le pic serique physiologique dˈhCG du premier trimestre serait decale vers le second trimestre. LˈhCG secretee serait hyperglycosylee ce qui modifierait sa demi-vie et sa clairance du compartiment maternel.

Inherited defects in the gene encoding the methylmalonyl-CoA mutase (MCM) result in the mut forms of methylmalonic aciduria (MMA). Twelve mutations have been identified associated with the mut(-) phenotype. We report two novel mutations (K621N and D156N) in a compound heterozygote mut(-) patient. These two mutations and three previously published ones (H627N, A191E, Y231N) were mapped onto a three-dimensional homology model of the human MCM constructed from the crystal structure of the Propionibacterium shermanii enzyme.

Resume Au cours du vieillissement, il existe une diminution globale de l'activite de l'axe somatotrope ; ce phenomene est appele somatopause. Il associe une diminution de la secretion de GH par l'hypophyse a une resistance peripherique a cette hormone, avec une diminution de l'expression des recepteurs a la GH, et par consequent une diminution de la production et de la concentration serique d'IGF-I. Par ailleurs, de nombreux autres phenomenes lies a l'âge comme la diminution de l'exercice physique, la diminution de la masse maigre au profit de la masse grasse ou un certain degre de malnutrition viennent renforcer l'abaissement de la production d'IGF-I. Les consequences de cette somatopause peuvent etre tres importantes au niveau des metabolismes osseux, musculaire et adipocytaire. Malgre des succes therapeutiques indeniables en termes d'augmentation de la masse maigre et d'effets sur le remodelage osseux, la therapie par la GH et/ou I'IGF-I souleve le probleme d'effets indesirables majeurs. Cette therapie serait donc reservee aux patients âges presentant un etat d'hypercatabolisme et/ou de denutrition.

Phenobarbital, a classical inducer of the drug-metabolizing cytochrome P450 genes, induces alpha1-acid glycoprotein gene expression through a PB-responsive element (PBRE) located at position -142 to -126 from the transcriptional start site. The aim of this study was to investigate nuclear protein binding to the PBRE sequence after PB treatment. Cycloheximide treatment showed that de novo protein synthesis was not required for PB to induce AGP gene expression, pointing to post-translational modifications. Studies of the DNA-protein complex with the PBRE showed that phosphorylation status is a key regulator of the binding capacity of transactivating proteins involved in PB transcriptional activation. This DNA-protein complex, analyzed by southwestern blotting and UV cross-linking, involves three nuclear factors with molecular weights of 43, 52, and 65 kDa. Supershift and competition experiments showed that the 43-kDa factor can be related to C/EBPalpha and the 52- and 65-kDa factors to the two subunits of NF-kappaB.

Objective: The objective of our study was to check if presence of fetal fibronectin in the cervical secretion of full term patient predicts accurately the onset of labour at term. Study design : 78 women in the term period were included in the study, serial samples for fetal fibronectin were assessed, each patient underwent spontaneous labor, delay between last sample and delivery were analysed. Results : Patient with positive fetal fibronectin delivered within 3 ± 1.9 days where as patient with negative fetal fibronectin delivered within 5.7 ± 3.9 days ( P = 0.01). Conclusion: Presence of fetal fibronectin in cervical secretions seems to be a powerful tool to predict in a short delay the onset of labour at term, it should be used in conjunction with clinical and fetal assessment data.

Antibodies directed against rat alpha1-acid glycoprotein (AGP) recognize a 70 kDa antigen, designated JB70, present in extracts of achlorophyllous Euglena gracilis cells as well as in their culture medium. By using 2-dimensional electrophoresis, JB70 appears to be composed of two acidic polypeptides. Additionally, Northern blot analysis reveals the presence in E. gracilis cells of a 2.3 kb mRNA hybridizing with a cDNA probe specific for rat AGP mRNA. Moreover, elevated mRNA levels are detected in dexamethasone-treated E. gracilis cells, indicating a response to this inducer similar to that observed for hepatic AGP. These results strongly suggest that polypeptides closely related to hepatic rat AGP are expressed in E. gracilis cells. They also indicate that, like other gene families implicated in natural defense processes such as heat-shock protein and metallothionein genes, the AGP gene appears to be conserved down to this early diverging eucaryote.

Resume L' Insulin-Like Growth Factor-I (IGF-I) a ete mis en evidence pour la premiere fois, en tant que facteur capable de stimuler l'incorporation de sulfates dans le cartilage et de se substituer a la GH pour cet effet, aussi bien dans des modeles in vitro qu' in vivo . Il est admis a l'heure actuelle que la plupart des effets de la GH sont medies par l'IGF-I dont la secretion est de type a la fois endocrine et autocrine/paracrine. L'IGF-I peut etre produit par une tres grande variete de types cellulaires mais la production hepatique est responsable d'environ 50% de l'IGF-I circulante. L'expression du gene de l'IGF-I est principalement controlee par la GH mais d'autres hormones, estradiol, androgenes et cortisol, sont impliquees dans cette regulation, de meme que l'etat nutritionnel. L'IGF-I, polypeptide de 70 acides amines de structure proche de celle de la proinsuline, est present dans la circulation et dans les espaces extracellulaires sous forme essentiellement liee (5% d'IGF-I libre dans le sang) a des proteines, de haute affinite, les Insulin-Like Growth Factor Binding Proteins (IGFBPs) dont six ont ete clonees et sequencees a ce jour. Les IGFBPs exercent plusieurs fonctions essentielles et, entre autres, assurent la regulation de sa biodisponibilite et de ses differentes activites biologiques. L'IGF-I exerce la plupart de ses effets cellulaires apres liaison a un recepteur specifique de structure voisine de celui de l'insuline. Les effets in vitro de l'IGF-I sont, d'une part, des effets anaboliques « rapides(metabolisme proteique et metabolisme des sucres) et, d'autre part, des effets mitogenes a plus long terme. L'IGF-I stimule la synthese d'ADN, la replication et la proliferation cellulaire ; il contribue a la differenciation de diverses lignees cellulaires et se comporte comme un agent inhibiteur de l'apoptose. In vivo , les effets mitogenes de l'IGF-I s'expriment globalement en termes d'activite de l'IGF-I au niveau de la croissance postnatale, ou il constitue le relais cellulaire essentiel aux effets attribues a la GH. Les effets metaboliques de l'IGF-I sont proches de ceux de l'insuline mais plus prolonges dans le temps du fait de la presence des IGFBPs.

Phenobarbital induces gene transcription of both cytochrome P450IIB (the barbiturate-inducible cytochrome P450 in mammals) and alpha 1-acid glycoprotein, one of the major acute-phase proteins in rats and humans. Analysis of the 5'-regulatory sequences of cytochrome P450IIB and alpha 1-acid glycoprotein genes in rats revealed the presence of a consensus sequence of 10 base pairs, termed the phenobarbital-responsive element or Barbie box, located in a region extending from positions -136 to -127 from the transcription start site of the alpha 1-acid glycoprotein gene. A 17-base pair oligonucleotide probe specific for alpha 1-acid glycoprotein and including the consensus sequence showed, in mobility shift assays, slight binding to liver nuclear protein from untreated animals. This binding was strongly and specifically increased with protein extracts from phenobarbital-treated rats. Transfection of rat primary hepatocytes with the pAGPcat construct induced basal expression of chloramphenicol acetyltransferase activity, which was increased by phenobarbital and dexamethasone treatment of cells. Induction of chloramphenicol acetyltransferase activity by phenobarbital was abolished when hepatocytes were transfected by constructs with a mutation or deletion of the Barbie box sequence. These results strongly suggest that the Barbie box sequence is involved in alpha 1-acid glycoprotein gene regulation by phenobarbital.

Phenobarbital (PB) induces transcription of the alpha 1-acid glycoprotein (AGP) gene, one of the major positive acute-phase proteins, the expression of which is controlled by a specific combination of glucocorticoids and cytokines. This raises questions as to the involvement of glucocorticoids and cytokine pathways in the PB-mediated effect on AGP gene expression. We found that the pattern of whole-serum proteins in PB-treated rats differed markedly from that observed during a typical acute inflammatory response (in turpentine-treated rats): levels of some positive acute-phase proteins (APP) increased slightly (alpha 1-acid glycoprotein, haptoglobin, hemopexin and T-kininogen), while levels of alpha 2 macroglobulin, the most sensitive marker of the acute-phase reaction, decreased. Among the negative APP, neither albumin nor prealbumin decreased while CBG increased. The cytokines involved in AGP gene regulation (mainly IL1, IL6 and TNF alpha) do not therefore seem to mediate the effect of PB on acute-phase protein expression. Glucocorticoid involvement is also ruled out by the observed enhancement of the effect of PB on AGP expression in adrenalectomized animals. Our results suggest that phenobarbital acts on AGP expression by a mechanism independent of the inflammatory pathway.

Lipogenesis from U(14C) lactate was studied in hepatocytes isolated from obese Zucker rats (fa/fa) their lean littermates (Fa/?) and Sprague Dawley rats. The distribution of radioactive carbon between the glycerol and the fatty acid moieties of the acylglycerols were studied. Radioactive lactate was better utilized for glycerol formation than it was for fatty acid formation in the obese rats. However, when oleate was added to the hepatocytic incubation medium, radioactive lactate was preferentially incorporated into the fatty acid moiety of the acylglycerols. Zucker obesity classified as a "metabolic obesity" by Meyer (1) depends upon abnormalities in carbohydrate metabolism associated with increased lipogenesis. This might be explained by biochemical shifts in the utilization of nutrients (2). Among the nutrients, lactate seems to be a better source of carbon than glucose for lipid synthesis (3). It has been shown that there is an increased hepatic portal blood concentration of lactate several hours after eating: about 4 mM in Wistar rats (4) and 10-15 mM in obese Zucker rats (3). We are interested in determinating the incorporation of carbon from lactate either into glycerol or into fatty acyl moieties of hepatic acylglycerols, and in determining the influence of exogenous fatty acids on acylglycerol synthesis, since a high level of circulating fatty acids in Zucker obese rats has been reported (5). Our purpose was to determine the incorporation of lactate into glycerol and fatty acyl moieties of acylglycerols, under the influence of oleate. Hepatocytes were isolated from ad libitum fed obese Zucker rats (fa/fa), their lean littermates (Fa/?) and Sprague-Dawley rats (SD). Incorporation of lactate was studied for three hours, in order to exclude short-term regulation effects and to allow oleate to be distributed into all cellular compartments.