• MeSH
• klinické laboratorní techniky normy   MeSH
• lidé MeSH
• odběr biologického vzorku normy   MeSH
• řízení kvality MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• směrnice MeSH

CYP3A4 is the most important drug-metabolizing enzyme that is involved in biotransformation of more than 50% of drugs. Pregnane X receptor (PXR) dominantly controls CYP3A4 inducibility in the liver, whereas vitamin D receptor (VDR) transactivates CYP3A4 in the intestine by secondary bile acids. Four major functional PXR-binding response elements of CYP3A4 have been discovered and their cooperation was found to be crucial for maximal up-regulation of the gene in hepatocytes. VDR and PXR recognize similar response element motifs and share DR3(XREM) and proximal ER6 (prER6) response elements of the CYP3A4 gene. In this work, we tested whether the recently discovered PXR response elements DR4(eNR3A4) in the XREM module and the distal ER6 element in the CLEM4 module (CLEM4-ER6) bind VDR/RXRalpha heterodimer, whether the elements are involved in the intestinal transactivation, and whether their cooperation with other elements is essential for maximal intestinal expression of CYP3A4. Employing a series of gene reporter plasmids with various combinations of response element mutations transiently transfected into four intestinal cell lines, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP), we found that the CLEM4-ER6 motif interacts with VDR/RXRalpha heterodimer and partially cooperates with DR3(XREM) and prER6 in both basal and VDR-mediated inducible CYP3A4 regulation in intestinal cells. In contrast, eNR3A4 is involved only in the basal transactivation in intestinal cells and in the PXR-mediated rifampicin-induced transactivation of CYP3A4 in LS174T intestinal cells. We thus describe a specific ligand-induced VDR-mediated transactivation of the CYP3A4 gene in intestinal cells that differs from PXR-mediated CYP3A4 regulation in hepatocytes.

• MeSH
• chromatinová imunoprecipitace MeSH
• cytochrom P-450 CYP3A genetika   MeSH
• DNA primery MeSH
• genetická transkripce fyziologie   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• receptory kalcitriolu fyziologie   MeSH
• regulace genové exprese enzymů fyziologie   MeSH
• sekvence nukleotidů MeSH
• střeva enzymologie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

Syncytin-1 is a captive envelope glycoprotein encoded by one of human endogenous retroviruses W. It is expressed exclusively in the placental trophoblast where it participates in cell-to-cell fusion during differentiation of syncytiotrophobast. In other tissues, however, syncytin-1 expression must be kept in check because inadvertent cell fusion might be dangerous for tissue organization and integrity. We describe here an inverse correlation between CpG methylation of syncytin-1 5' long terminal repeat and its expression. Hypomethylation of the syncytin-1 5' long terminal repeat in the placenta and in the choriocarcinoma-derived cell line BeWo was detected. However, other analyzed primary cells and cell lines non-expressing syncytin-1 contain proviruses heavily methylated in this sequence. CpG methylation of syncytin-1 is resistant to the effect of the demethylating agent 5-azacytidine. The inhibitory role of CpG methylation is further confirmed by transient transfection of in-vitro-methylated syncytin-1 promoter-driven reporter construct. Altogether, we conclude that CpG methylation plays a principal role in the transcriptional suppression of syncytin-1 in non-placental tissues, and, in contrast, demethylation of the syncytin-1 promoter in trophoblast is a prerequisite for its expression and differentiation of multinucleated syncytiotrophoblast.

• MeSH
• buněčné linie MeSH
• CpG ostrůvky fyziologie   MeSH
• down regulace imunologie   MeSH
• financování organizované MeSH
• genové produkty env antagonisté a inhibitory   biosyntéza   genetika   MeSH
• HeLa buňky MeSH
• koncové repetice MeSH
• lidé MeSH
• metylace DNA MeSH
• placenta metabolismus   MeSH
• promotorové oblasti (genetika) MeSH
• těhotenské proteiny antagonisté a inhibitory   biosyntéza   genetika   MeSH
• transkripční faktory antagonisté a inhibitory   biosyntéza   genetika   MeSH
• trofoblasty metabolismus   MeSH
• Check Tag
• lidé MeSH