NR2F1 and IRE1beta suppress microsomal triglyceride transfer protein expression and lipoprotein assembly in undifferentiated intestinal epithelial cells.
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Oestrogen facilitates the binding of ubiquitous and liver-enriched nuclear proteins to the apoVLDL II promoter in vivo.
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Using genomic and in vitro DNasel footprinting, we have analyzed protein-DNA interactions within the promoter region of the oestrogen-inducible gene encoding chicken apoVLDL II. The footprints coincide with previously detected guanosine-protein contacts in vivo. All footprints identified are present in the apoVLDL II-expressing liver exclusively and absent in hormone-naive liver, spleen and oviduct. They comprise recognition sites for the oestrogen receptor, the ubiquitous COUP-transcription factor, the liver-enriched C/EBP and/or DBP and the liver-specific LF-A1. In vitro, binding of protein to the oestrogen response element (ERE) is excluded by the prior binding of a protein, possibly C/EBP or DBP, to an adjacent element. The recognition sequence of the COUP-TF is also a target for LF-A1. The results suggests that oestrogen-dependent liver specific activation of the apoVLDL II promoter is established by the binding of the oestrogen receptor to EREs and multiple liver-enriched factors (C/EBP, DBP and LF-A1) to their nearby recognition sequences. Apparently, several DNA binding nuclear proteins cooperate to keep the promoter in a state that is accessible for the RNA polymerase complex. (+info)
Area-specific temporal control of corticospinal motor neuron differentiation by COUP-TFI.
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Chicken ovalbumin upstream promoter transcription factor binds to a negative regulatory region in the human immunodeficiency virus type 1 long terminal repeat.
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The human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) contains a negative regulatory element (NRE) which downregulates the rate of LTR-directed transcription and HIV-1 replication. Within the NRE is a GGTCA palindrome, which binds a possible member of the steroid/thyroid hormone receptor superfamily. Mutation of this site leads to an increase in LTR-directed transcriptional activity compared with the wild type, consistent with the element's being a functional part of the NRE. The palindrome contains significant identity to the chicken ovalbumin upstream promoter (COUP) element to which COUP transcription factors (COUP-TFs), members of the steroid/thyroid hormone receptor superfamily, bind. We demonstrate here that human COUP-TFs can bind specifically to this HIV-1 COUP-like element in a manner identical to binding to ovalbumin COUP. We show that the predominant COUP-TF family member synthesized in T cells is the 68-kDa form, which is likely to be responsible for any in vivo function of the HIV-1 COUP-like element in these cells. Finally, we have identified three HIV-1 variant strains that contain mutations in the HIV-1 COUP-like element which affect the binding affinity of COUP-TF for these variant COUP elements. (+info)
Generation of ES cells for conditional expression of nuclear receptors and coregulators in vivo.
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