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)

Previous studies have shown that the gonadotropins follicle-stimulating hormone and luteinizing hormone stimulate proopiomelanocortin (POMC) promoter activity and mRNA levels in ovarian granulosa cells. The objective of these studies was to determine the role of cAMP-dependent protein kinases (pKA) in gonadotropin-stimulated gene expression. Primary cultures of rat granulosa cells were transfected with a gene construct consisting of the POMC promoter (-150 to +63; designated pOMC-CAT) fused to the chloramphenicol acetyltransferase (CAT) reporter gene either alone or cotransfected with an expression plasmid (designated mutant RI), which overexpresses a mutant form of the murine RI subunit incapable of binding cAMP and serving as an irreversible inhibitor of the catalytic subunit of pKA. Follicle-stimulating hormone or isoproterenol caused a significant stimulation of pOMC-CAT activity in transfected cells. Cotransfection of pOMC-CAT with mutant RI caused a significant inhibition of basal pOMC-CAT activity and abolished the gonadotropin stimulation. As a control, transfection of the SV-40 viral enhancer-promoter fused to CAT (pSV2-CAT) was unresponsive to follicle-stimulating hormone stimulation and cotransfection with mutant RI had no significant effect on pSV2-CAT activity. These studies suggest that gonadotropin regulation of the POMC promoter is mediated by pKA and that promoter activity is stringently controlled by pKA.
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PMID:Intracellular mechanisms of gonadotropin-stimulated gene expression in granulosa cells. 165 68

Gonadotropins (follicle-stimulating hormone (FSH), luteinizing hormone, and human chorionic gonadotropin) and beta-adrenergic agonists have been shown to stimulate expression of the proopiomelanocortin (POMC) gene in ovarian granulosa cells. The current studies investigate the intracellular mechanisms by which gonadotropins regulate gene expression. Primary cultures of rat granulosa cells were transfected with the plasmid POMC-CAT-150, which expresses the chloramphenicol acetyltransferase (CAT) reporter gene under the regulation of the rat POMC 5'-flanking region. CAT activity was stimulated by treatment of the cells with either 20 ng/ml FSH or 1 microM isoproterenol. To assess the role of protein kinase A (ATP:protein phosphotransferase; EC 2.7.1.37) in the gonadotropin and adrenergic response, an expression vector, MtR-AB, encoding a mutant RI regulatory subunit was cotransfected with POMC-CAT-150. The mutant protein kinase A regulatory subunit encoded by MtR-AB lacks functional cAMP-binding sites but effectively binds and specifically inhibits the catalytic activity of protein kinase A. The results of this analysis demonstrated that gonadotropin and adrenergic agonist stimulation of the POMC-CAT reporter construct in primary cultures of rat granulosa cells were abolished by cotransfection with MtR-AB; whereas a control SV40-promoter construct was unaffected by either gonadotropin treatment or cotransfection with MtR-AB. Basal expression directed by the POMC promoter was also decreased by cotransfection with the MtR-AB, implying that basal expression from the POMC promoter may also depend on protein kinase A. Deletion analysis of the POMC sequence indicated regions (-40 to -33 and +4 to +63) important for basal and FSH-stimulated expression. These studies suggest that both gonadotropin and adrenergic stimulation of the POMC promoter are mediated by protein kinase A and that regions proximal to the promoter are essential for gonadotropin-regulated expression from the promoter.
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PMID:Specific inhibition of protein kinase A in granulosa cells abolishes gonadotropin regulation of the proopiomelanocortin promoter. 190 60

The androgen receptor (AR) is a developmental and tissue-specific transcription factor which is activated by binding testosterone or dihydrotestosterone. Several different methods of transcriptional regulation of the AR have been shown, including regulation by androgens, follicle-stimulating hormone, epidermal growth factor, and the cAMP pathway. In order to further characterize the transcriptional regulation of the AR, portions of the mouse androgen receptor (mAR) promoter were cloned into the promoterless pBLCAT3 vector and assayed for chloramphenicol acetyltransferase activity. The results indicate that in addition to the previously characterized promoter (+1) there is a second distinct promoter located 3' to the first promoter. Amplification of the 5'-end of the AR gene indicates that RNA originating from the second promoter is initiated from 162 and 170 bases downstream from the 5'-most previously characterized site. Northern blot analysis indicated that RNA initiated from the two promoters is differentially expressed in several cell lines and multiple tissues. Androgen ablation by castration showed that both promoters are controlled by androgens in the kidney. Sequence analysis revealed that the second promoter does not contain a TATA or CAAT box. Further characterization of this promoter may provide important insights into the transcriptional regulation of the androgen receptor since previous studies have often included only the first promoter.
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PMID:The mouse androgen receptor gene contains a second functional promoter which is regulated by dihydrotestosterone. 798 Dec 21

The promoter of the rat prostaglandin endoperoxide synthase 2 (PGS-2) gene has recently been shown to confer gonadotropic hormone (follicle-stimulating hormone (FSH), luteinizing hormone (LH), cAMP) inducibility when ligated to a CAT (chloramphenicol acetyltransferase) reporter gene and transfected into primary cultures of differentiated granulosa cells. To delineate cis-acting elements and trans-activating factors mediating this response, deletions of the active promoter region (-192/-53 base pairs upstream of the transcriptional start site) were tested for their ability to bind protein of granulosa cell nuclear extracts and activate reporter gene activity. Electrophoretic mobility shift assays revealed that the DNA subregion -142/-120 inhibited protein/DNA binding observed between granulosa cell nuclear extracts and the labeled PGS-2 fragment -192/-53. The subregion -142/-120 acting element C/EBP beta, 5'-TTATGCAAT-3'. Point mutations within the C/EBP beta element abolished protein/DNA binding and resulted in a 50% loss of forskolin/LH/FSH inducibility of reporter gene activity. C/EBP beta mRNA and protein were induced rapidly in granulosa cells in vivo by an ovulatory dose of human chorionic gonadotropin (hCG). Collectively, these results indicate that C/EPB beta appears to play a key role in regulating induction of the PGS-2 gene in granulosa cells prior to ovulation.
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PMID:Transcriptional regulation of the rat prostaglandin endoperoxide synthase 2 gene in granulosa cells. Evidence for the role of a cis-acting C/EBP beta promoter element. 840 49

Prostaglandin endoperoxide synthase isoform 2 (PGS-2) mRNA and protein are transiently induced by gonadotropins in granulosa cells of preovulatory follicles prior to ovulation. To better understand the hormonal regulation of the rat PGS-2 (rPGS-2) gene in these cells, genomic clones containing rPGS-2 as well as up to 6 kilobases of 5'-flanking DNA were isolated by screening a rat liver genomic library with a labeled 5'-fragment of the mouse PGS-2 cDNA. Primer extension analysis using ovarian follicular mRNA identified the presence of a single rPGS-2 transcription initiation site located 144 nucleotides upstream of the ATG translation initiation codon. To test for promoter activity within the 5'-flanking region of the rPGS-2 gene, a genomic fragment, -2698/32 (1 = cap site), as well as a series of 5'-deletion mutants, were fused upstream of the chloramphenicol acetyltransferase (CAT) reporter gene and transfected into primary cultures of granulosa cells. Forskolin (7.5 microM), follicle-stimulating hormone (500 ng/ml) and luteinizing hormone (500 ng/ml) induced CAT activity following transfection with the -2698/32PGS.CAT, whereas gonadotropin-releasing hormone (10(-6) M) and interleukin-1 beta (30 ng/ml) had no effect. Deletion mutants delineated the region spanning from -192 to -54 of the transcription start site to be essential for both basal and forskolin-regulated expression of the reporter gene. The same DNA fragment (-192/-54) exhibited specific binding to granulosa cell nuclear extract proteins as analyzed by electrophoretic mobility shift assays. Additional specific bands were observed in extracts prepared from granulosa cells exposed to an ovulatory dose of gonadotropin. Collectively, these results provide the first structural and functional evidence that the transcriptional regulation of the rat PGS-2 gene by gonadotropins and forskolin in granulosa cells involves 5'-flanking DNA sequences, specifically a region between -192 and -54 of the transcription initiation site.
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PMID:Characterization and hormonal regulation of the promoter of the rat prostaglandin endoperoxide synthase 2 gene in granulosa cells. Identification of functional and protein-binding regions. 850 40