 A one-nucleotide difference in a cAMP and phorbol ester response element leads to differential regulation of the human chorionic somatomammotropin A and B gene transcriptionOury, Cécile  ; ; et alin Journal of Molecular Endocrinology (1997), 18(2), 87-99 Human chorionic somatomammotropin (hCS) is encoded by two highly related genes, hCS-A and hCS-B, located in the hGH/hCS gene locus. Both genes are expressed in the syncytiotrophoblast layer of the ... [more ▼] Human chorionic somatomammotropin (hCS) is encoded by two highly related genes, hCS-A and hCS-B, located in the hGH/hCS gene locus. Both genes are expressed in the syncytiotrophoblast layer of the placenta and hCS release from trophoblast cells is known to be increased by cAMP and phorbol esters. However, it remains unclear whether this regulation acts at the level of hCS gene expression or secretion and whether both genes are affected. We examined the effects of cAMP and phorbol 12-myristate 13-acetate (PMA) on the transcription of the hCS-A and hCS-B genes. Transient expression experiments revealed a 7 bp cAMP- and PMA-responsive element (CRElhCS-A) spanning nucleotides-1102 to -1096 upstream of the hCS-A gene. In contrast, the homologous sequence upstream of hCS-B (CRElhCS-B), differing from CRElhCS-A by a single substitution, shows little or no response to cAMP. In band-shift assays, the CRElhCS-A oligonucleotide was shown to bind two factors related to CREBP and AP-1, whereas CRElhCS-B only competes for one of these complexes. Finally, Southwestern analysis revealed that the CRElhCS-A element binds two ubiquitous proteins of 100 kDa and 47 kDa respectively, whereas CRElhCS-B interacts only with the 47 kDa protein. Taken together, these results suggest that a 47 kDa protein binding to the CRElhCS-A and CRElhCS-B elements is involved in the PMA response of the hCS-A and hCS-B genes, and a 100 kDa protein plays a crucial role in cAMP regulation of the hCS-A gene. [less ▲] Detailed reference viewed: 21 (4 ULg)The enhancers of the human placental lactogen B, A, and L genes: progressive activation during in vitro trophoblast differentiation and importance of the DF-3 element in determining their respective activities; ; Oury, Cécile et alin DNA & Cell Biology (1996), 15(10), 845-54 The hCS-A and hCS-B genes encoding human chorionic somatomammotropin and the related hCS-L gene are very similar in their coding and flanking sequences. For each of these genes, downstream enhancers ... [more ▼] The hCS-A and hCS-B genes encoding human chorionic somatomammotropin and the related hCS-L gene are very similar in their coding and flanking sequences. For each of these genes, downstream enhancers, varying in strength, have been identified with the help of cytotrophoblast-derived JEG-3 cells, which do not express the hCS genes. Here we study the activity of the hCS enhancers in human syncytiotrophoblast in primary culture, which naturally expresses the hCS genes. We show that the activity of the hCS-B gene enhancer is mediated by two elements, DF-3 and DF-4, whereas the hCS-L and hCS-A gene enhancers display weaker activity due to mutations in their respective DF-3 sites. Replacement of the hCS-B DF-3 site with the homologous hCS-A sequence causes hCS-B enhancer activity to decrease. Primary cytotrophoblasts differentiate in culture to form the syncytiotrophoblast. We show that during this process the production of hCS progressively increases and that concomitantly all three hCS enhancers are progressively activated. A targeted mutation in the 3' part of the DF-4 element abolishes the binding of a protein present only in syncytiotrophoblast extracts and inactivates the DF-4 element. Thus, a direct correlation exists between the appearance of this syncytiotrophoblast-specific protein and hCS enhancer activity. This primary culture model proves useful in studying the regulation of the hCS genes. [less ▲] Detailed reference viewed: 16 (6 ULg)A TEF-1 binding motif that interacts with a placental protein is important for the transcriptional activity of the hCS-B enhancer; Oury, Cécile ; et alin DNA & Cell Biology (1994), 13(10), 1037-45 The transcriptional activity of the human placental lactogen genes (choriosomatomammotropic hormone, hCS) is controlled by tissue-specific enhancers located 4 kb downstream from their respective origins ... [more ▼] The transcriptional activity of the human placental lactogen genes (choriosomatomammotropic hormone, hCS) is controlled by tissue-specific enhancers located 4 kb downstream from their respective origins of transcription. The hCS-B enhancer is the strongest; its activity is mediated by synergism between two protein-binding sites (DF-3 and DF-4). The DF-4 site possesses a potential binding sequence for TEF-1, a known transcription factor. In this paper, we show by electrophoretic mobility-shift assays and antibody supershift experiments that TEF-1 does not bind to site DF-4. Mutations in the TEF-1-like binding motif of site DF-4 prevent formation of the DNA-protein complex, called complex f, in the presence of placental JEG-3 cell extracts. When HeLa cell extracts are used, another complex (complex c) is also affected. In transient expression experiments, TKCAT constructs linked to this mutated DF-4 site exhibit greatly reduced transcriptional activity when introduced into JEG-3 cells. Some cell lines contain both protein c and protein f (the proteins forming complexes c and f); when transfected, these lines display reduced DF-4-driven activity, suggesting that the two proteins could compete for the same DF-4 sequence. We conclude that protein f is important for the placenta-specific activity of the hCS-B enhancer. By UV cross-linking, we show that protein f is actually three polypeptides ranging in size from about 12 to 21 kD. [less ▲] Detailed reference viewed: 21 (2 ULg)The Transcriptional Regulation of the Growth Hormone Gene Is Conserved in Vertebrate Evolution; ; et al in Biochemical and Biophysical Research Communications (1993), 192(3), 1360-1366 Growth hormone (GH) gene expression in mammals is regulated by the interaction of the transcription factor Pit-1 with two binding sites within the proximal promoter. Four sequences, homologous to the ... [more ▼] Growth hormone (GH) gene expression in mammals is regulated by the interaction of the transcription factor Pit-1 with two binding sites within the proximal promoter. Four sequences, homologous to the mammalian Pit-1 motif occur in the rainbow trout (Oncorhynchus mykiss) GHII (rtGH) gene promoter, two of which partly overlap. The three regions containing these putative Pit-1 binding sequences were protected from deoxyribonuclease I digestion by nuclear extracts of GC cells, a rat pituitary tumor cell line producing Pit-1. In gel shift assays, nuclear proteins from GC cells and from trout pituitaries were found to interact specifically with one of these protected sites. Transfection experiments showed that the rtGH promoter is transcnptionally active in GC cells, the response being strongly enhanced in the presence of a cAMP analogue. The results demonstrate that rat Pit-1 binds to and activates the rtGH promoter, indicating that the basic mechanisms regulating GH gene transcription have been conserved between fish and mammals. [less ▲] Detailed reference viewed: 5 (2 ULg)Efficient lipofection of human trophoblast cells in primary cultures; ; Oury, Cécile et alin Biochemical and Biophysical Research Communications (1993), 196(1), 376-81 Human choriosomatomammotropic hormone, also known as placental lactogen, is expressed in syncytiotrophoblast cells of the placenta. Studying transcriptional regulation of the genes coding for this hormone ... [more ▼] Human choriosomatomammotropic hormone, also known as placental lactogen, is expressed in syncytiotrophoblast cells of the placenta. Studying transcriptional regulation of the genes coding for this hormone, we became interested in transfecting primary cultures of these trophoblast cells. In this study, we show that it is possible to transfect, by the lipofection method, these giant cells in an efficient and reproducible manner. We show the presence of an enhancer region downstream from the hCS-B gene, functionally active in these cells; furthermore, we demonstrate the placenta-specific characteristic of this enhancer, previously identified in a human choriocarcinoma cell line. [less ▲] Detailed reference viewed: 16 (7 ULg)Bovine Leukemia Virus - related antigens lymphocyte cultures infected with AIDS - associated viruses; ; et al in Science (1985), 227 Detailed reference viewed: 11 (5 ULg)Evolution de la rétention d'eau et de la morphologie de la fibre au cours de l'hydrolyse enzymatique de la cellulosePaquot, Michel ; Thonart, Philippe ; et alin Holzforschung : International Journal of the Biology, Chemistry, Physics, & Technology of Wood (1981), 35 Detailed reference viewed: 10 (1 ULg) |
||
