Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To characterize the transcriptional effects of human (h)FSH and hCG on the POMC gene, primary rat granulosa cells were transiently transfected with a chloramphenicol acetyltransferase (CAT) reporter plasmid under the control of the POMC promoter and 5' region. POMC-CAT contains a fragment of the rat POMC gene, extending from nucleotide -704 to nucleotide +63, fused to the CAT gene. Treatment of POMC-CAT-transfected cells with either hFSH (20 ng/ml) or hCG (10 ng/ml) significantly increased CAT enzyme activity; however, neither hCG nor hFSH increased CAT enzyme activity in cells transfected with pSV2-CAT, a reporter plasmid under the control of the SV40 virus promoter and 5' region. The phosphodiesterase inhibitor isobutylmethylxanthine or the nonhydrolyzable cAMP analog cAMP-chlorothiophenyl significantly increased CAT activity in POMC-CAT-transfected granulosa cells. Human FSH stimulated transcription 10, 20, and 40 h after treatment, but FSH stimulation at the two earlier time points was 2.5- to 5.5-fold greater than that at 40 h. Gonadotropin-stimulated steroidogenesis was equivalent in POMC-CAT-transfected granulosa cells, untransfected, and mock-transfected cells. This indicates that transfection left the physiological hormone response intact. These data demonstrate the following. 1) 767 basepairs of the rat POMC gene are enough to confer gonadotropin stimulation on the CAT marker gene in granulosa cells. 2) Although the POMC promotor lacks a well conserved cAMP response element, either of two different pharmacological manipulations of granulosa cells that raise intracellular cAMP can also stimulate POMC-driven CAT expression. 3) Transfected primary cultures of granulosa cells provide a nontransformed, physiologically relevant model with which to study hormone-regulated gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Gonadotropin regulation of the rat proopiomelanocortin promoter: characterization by transfection of primary ovarian granulosa cells. 246 53

DNA elements governing transcription of the ovine cytochrome P-450 side-chain cleavage (CYP11A1) gene were investigated. Three overlapping genomic clones for the ovine CYP11A1 gene were isolated and characterized. The transcriptional start site was located 51 nucleotides upstream from the initiating methionine. Gene transfer experiments were conducted in murine adrenocortical Y1 cells and human choriocarcinoma JEG-3 cells using chloramphenicol acetyltransferase reporter gene constructs containing promoter fragments from -2700 to -177 bp. The results demonstrate that DNA elements sufficient to convey a basal level of expression and cyclic AMP (cAMP) responsiveness lie within 177 bp of the transcriptional start, although the possibility that additional regulatory elements reside outside this 177 bp has not been excluded. The ovine 5' flanking sequence demonstrated 92% homology with the bovine sequence, extending over the entire fragment. In contrast, only four significant regions of conservation between the ovine, murine, rat and human CYP11A1 promoters were found. These regions are positioned within 200 bp upstream of the transcriptional start site. DNase 1 footprinting was performed to identify DNA elements able to bind nuclear proteins. Primary adrenocortical and placental tissues from sheep were used as the source of nuclear extracts to detect DNA-protein interactions relevant to CYP11A1 gene expression in vivo. Five regions of protection were detected in the first -634 bp of the ovine CYP11A1 promoter. Three of these elements corresponded to the regions which are well-conserved between species. The other two elements resembled activating protein-1 (AP-1) and AP-4 sites and overlapping AP-2/Sp1 sites, and are conserved in the bovine gene but not in other species. Nuclear protein extracts from adrenals of sheep with different serum ACTH levels (i.e. ACTH-treated, dexamethasone-treated and untreated sheep) protected similar regions of the ovine CYP11A1 promoter fragment. Similarly, the regions protected did not differ when nuclear protein from JEG-3 cells treated with cAMP was compared with that of untreated JEG-3 cells. These results suggest that induction of CYP11A1 gene transcription by ACTH in the ovine adrenal and by cAMP in JEG-3 cells in culture is not mediated by changes in binding of the proteins that interact directly with these footprinted elements. The elements footprinted by extracts from primary ovine tissue lie within the 177 bp sufficient for cAMP-regulated expression. The correspondence of these elements either to regions conserved between species or to known consensus binding sites suggests that these sequences are cis elements involved in regulating transcription of the ovine CYP11A1 gene in vivo.
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PMID:Molecular cloning and characterization of the cyclic AMP-responsive ovine CYP11A1 (cholesterol side-chain cleavage) gene promoter: DNase 1 protection of conserved consensus elements. 837 14

The present study was designed to examine the role of the nurr1/nur77 subfamily of nuclear receptor transcription factors in the regulation of the hypothalamic/pituitary/adrenal axis at the neuroendocrine level. We demonstrate that this nuclear receptor subfamily can regulate the expression of the CRF and POMC genes by interacting with a specific cis-acting sequence in their proximal promoter regions. To examine the physiological significance of this response, we have focused on the POMC gene. We provide evidence that nurr1 and nur77 are rapidly induced by CRF in primary pituitary cells and that this induction is mimicked by forskolin in an anterior pituitary cell line. Further, we demonstrate that both nurr1- and forskolin-dependent induction of a POMC-chloramphenicol acetyltransferase reporter gene are inhibited by mutation of the nurr1-binding site within the POMC promoter and that this site alone can confer cAMP responsiveness to a heterologous promoter. Finally, we provide evidence that the nurr1/nur77 response sequence is pivotal to both nurr1/nur77-dependent positive regulation and glucocorticoid receptor-dependent negative regulation of the POMC gene. These data strongly support the conclusion that the nurr1/nur77 subfamily plays an important coordinate neuroendocrine-regulatory role at all levels of the hypothalamic/pituitary/adrenal axis.
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PMID:Neuroendocrine regulation of the hypothalamic pituitary adrenal axis by the nurr1/nur77 subfamily of nuclear receptors. 899 86

The MVDP (mouse vas deferens protein) gene, which encodes an aldose reductase-like enzyme, is mainly expressed in vas deferens epithelium and adrenal cortex. Vas deferens MVDP gene transcription was known to be under androgenic control, we now have evidence for androgen and probable ACTH responsiveness of the MVDP gene in the adrenal. To analyze the role of potential regulatory regions in hormonal, developmental, and tissue-specific aspects of MVDP regulation, we generated transgenic mice harboring MVDP-CAT fusion genes. The constructs carried either -1.8 or -0.5 kb 5'-flanking sequence attached to the chloramphenicol acetyltransferase gene in presence or absence of a 3.5-kb intragenic fragment in a downstream position. We show that at least two regions ensure proper gene regulation in vivo. The first, located within the 1.8-kb promoter fragment, directs tissue specificity; positive elements necessary for vas deferens and adrenal expression lay within positions -1804 to -510 and -510 to +41, respectively. The second, located within the 3.5-kb intragenic fragment spanning intron 1 to intron 2, increases percentage of expressing lines and behaves as a vas deferens-specific enhancer. Hormonal and developmental control of transgenes closely parallel endogenous gene regulation. Androgen and ACTH responsiveness in adrenals is conferred by 0.5-kb promoter, whereas in vas deferens, full androgenic response of the 1.8-kb promoter required the 3.5-kb intragenic fragment. Thus, vas deferens and adrenals use distinct cis-acting elements to direct and regulate the expression of the MVDP gene.
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PMID:5'-flanking and intragenic sequences confer androgenic and developmental regulation of mouse aldose reductase-like gene in vas deferens and adrenal in transgenic mice. 1006 61