Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The CYP11A1 gene encodes the cholesterol side-chain cleavage enzyme P450scc, which catalyzes the synthesis of steroids from cholesterol. This gene is expressed only in steroidogenic organs such as the adrenal, gonad, placenta, and brain. We have characterized an upstream regulatory element of the human CYP11A1 gene, termed AdE, which contributed to its cell type-specific expression. The AdE sequence contains two protein binding regions, AdE1 and AdE2, which bind many proteins including NF1- and Sp1-like proteins as shown by electrophoretic mobility shift assay, footprinting, competition, antibody supershift, and mutagenesis of the binding sites. When cloned in front of the CYP11A1 promoter or the heterologous thymidine kinase promoter, AdE sequences enhanced expression of the reporter gene in steroidogenic cell lines of the adrenal, gonad, and placental origin but not in nonsteroidogenic cell lines such as COS-1 and Rat-1. The function of AdE1 and AdE2 was lower when present individually than together. The combined action of multiple transcription factors binding to the AdE sequence brings about the final activation of the CYP11A1 gene in a tissue-specific manner.
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PMID:Characterization of the upstream sequence of the human CYP11A1 gene for cell type-specific expression. 870 23

Expression of the ovine P-450 side-chain cleavage enzyme gene (CYP11A1) is stimulated by epidermal growth factor (EGF) through a pathway that involves c-Jun in JEG-3 placental cells. Growth factor signaling involves ras-dependent and ras-independent signaling pathways, which in turn regulate gene transcription through related but distinct mitogen-activated protein kinase pathways (MAPKs) including the extracellular signal-regulated kinases (ERKs) and the stress-activated protein kinases (SAPKs). We investigated the intracellular signaling pathways governing EGF induction of the CYP11A1 promoter. EGF stimulation of the CYP11A1 promoter (4-fold) was reduced 60% by a dominant negative mutant of ras (N17), and 30-40% by antisense ras. EGF induced both ERK and SAPK activity in JEG-3 cells. EGF-induced CYP11A1 promoter activity was reduced 60% by the MEK1 inhibitor PD098059 and 50% by a dominant negative mutant of the ERK-specific regulator MEK1. In contrast, dominant negative mutants of the SAPK-specific activator, SEK1, induced a further increase in EGF-induced CYP11A1 promoter activity. Constitutively active mutants of ras (V12 or L61) increased CYP11A1 promoter activity 6- to 8-fold. Deletion of the EGF response element (EGF-RE) between -92 and -77 bp reduced ras induction by 60%; however, a residual 3-fold induction remained through the proximal -77 bp. Mutation of the EGF-RE AP-1-like sequence in the context of the native promoter reduced CYP11A1 promoter activation by ras 60%. The EGF-RE sequence was sufficient for 6-fold activation by ras in the context of an heterologous thymidine kinase promoter. Candidate transcription factor targets (c-Jun, c-Ets-2) for the ras-signaling cascade were examined for their effects on CYP11A1 promoter activity. Overexpression of c-Jun induced the CYP11A1 promoter through the EGF-RE; however, c-Ets-2 activation of the CYP11A1 promoter (12-fold) required the proximal ras-responsive promoter sequences that are distinct from the EGF/MEK/c-Jun-responsive element. Induction of the CYP11A1 promoter by EGF involves a ras/MEK1/AP-1-dependent pathway that is distinct from induction by ras/c-Ets-2.
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PMID:Stimulation of the P-450 side chain cleavage enzyme (CYP11A1) promoter through ras- and Ets-2-signaling pathways. 888 43

Cytochrome P450scc catalyzes the important first step in the steroid synthesis pathway; however, it is clear that additional factors regulating the temporal and spacial specific expression of the CYP11A1 gene remain to be identified. To isolate novel transcription factors that regulate this gene, a cis-acting element of the 5'-flanking region from nucleotides -155 to -131 (-155/-131) was used to screen a human placental lambda gt11 cDNA expression library, and an interacting clone was isolated. The open reading frame of the cDNA encodes several domains that are characteristic of transcription factors including an acidic region, a region rich in prolines and three zinc-finger motifs. Expression of the cDNA by in vitro transcription/translation and by transient transfection in HeLa cells yielded a protein of 132 kDa, which concurs with the predicted size. Transfection of the cDNA in placental JEG-3 and adrenal NCI-H295 cells, stimulate expression of a reporter construct controlled by the P450scc gene 5'-flanking region from nucleotides -1676 to +49. This transcriptional regulating protein of 132kDa (TReP-132) when expressed in HeLa cells was demonstrated to interact with the -155/-131 region in bandshift analysis, and tandem copies of this region was shown to confer activation of the heterologous HSV thymidine kinase minimal promoter. Coexpression of CBP/p300 with TReP-132 further increased promoter activity, and the proteins were demonstrated to interact physically. RNA analysis demonstrated the highest levels of expression in the adrenal cortex and testis; and transcript expression is also found in the steroidogenic JEG-3, NCI-H295, and MCF-7 cell lines, but not in non-steroidogenic HepG2 and HK293 cells. Subsequently it has been shown that TReP-132 interacts with steroidogenic factor-1 (SF-1) through specific domains; and along with the interaction with CBP/p300 these factors are postulated to form a complex to regulate expression of the P450scc gene.
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PMID:Function of the transcriptional regulating protein of 132 kDa (TReP-132) on human P450scc gene expression. 1253 Jun 63