Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The formation of estrogens from C19 steroids is catalyzed by a specific form of cytochrome P450, aromatase cytochrome P450 (P450AROM; the product of the CYP19 gene). Previous studies have demonstrated that aromatase activity in human adipose and ovarian granulosa cells is subject to complex multifactorial regulation and that changes in activity are correlated with changes in the levels of mRNA encoding P450AROM. We have previously isolated the human CYP19 gene. Two unique untranslated first exons (exons I.1 and I.2) have been identified in mRNA specific for P450AROM in human placenta. Although the proportion of transcripts encoding exon I.2 is very small, genomic clones encoding the sequences of both exons I.1 and I.2 have recently been isolated. The corpus luteum of human ovary differs in that promoters I.1 and I.2 are completely inactive. Sequence analysis of the DNA immediately 5' of exon II (which contains the start site of translation) demonstrates the presence of a TATAA sequence beginning 149 basepairs 5' of the ATG initiation codon identified in placental exon II. Using a combination of primer extension and S1 nuclease protection analysis, it appears that the initiation site of ovarian P450AROM transcripts aligns 26 basepairs down-stream of the sequence TATAA. It appears, therefore, that the expression of P450AROM-specific mRNA in corpus luteum is regulated by an additional promoter (promoter II), which is located just 5' of exon II. Consistent with these observations, Northern analysis of poly(A)+ RNA isolated from placenta and corpus luteum demonstrates that the major promoter of placental P450AROM is promoter I.1, while the major promoter in the corpus luteum is promoter II.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tissue-specific promoters regulate aromatase cytochrome P450 gene expression in human ovary and fetal tissues. 172 89

The biosynthesis of estrogens from androgens is catalyzed by a enzyme of the endoplasmic reticulum termed aromatase cytochrome P-450 (P-450AROM). The gene encoding P-450AROM was isolated in our laboratory utilizing a full-length P-450AROM cDNA and a primer-extended cDNA obtained from human placental libraries as probes. We have found that the P-450AROM gene spans at least 75 kilobases and the region encoding the P-450AROM protein is comprised of nine exons. In addition, there are at least two untranslated exons, I.1 and I.2, upstream of which are found putative promoter sequences thought to be responsible for expression of P-450AROM in placenta. To determine if these promoters are utilized to regulate P-450AROM expression in adipose tissue, we have used polymerase chain reaction technology in an attempt to amplify the untranslated exons out of human adipose total RNA. The untranslated exons could not be amplified out of adipose RNA although they could be amplified out of placental RNA. When oligonucleotides corresponding to these untranslated exons were used in Northern analysis of RNA from human adipose stromal cells, no hybridizable mRNA species was detectable. Putative promoter sequences 326 and 110 base pairs (bp) upstream of the 5' end of exon II were evaluated as adipose P-450AROM promoters by primer extension analysis and S1 nuclease protection assays. Both methods suggest a start site of transcription 26 bp down-stream of the TATAAA sequence located 110 bp from the placental intron-exon II junction. These results indicate that tissue-specific regulation of aromatase activity in the human is achieved in part by the use of alternative transcriptional start sites and tissue-specific promoters.
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PMID:Tissue-specific expression of human P-450AROM. The promoter responsible for expression in adipose tissue is different from that utilized in placenta. 204 Jun 33

The biosynthesis of estrogens is catalyzed by aromatase P450 (P450arom), the product of the CYP19 gene. The tissue-specific expression of the CYP19 gene is regulated by means of tissue-specific promoters through the use of alternative splicing mechanisms. Thus, transcripts containing various 5'-untranslated termini are present in human placenta and other fetal tissues, ovary, brain, and adipose stromal cells. Sequence corresponding to untranslated exon 1.4 is present in 5'-termini of transcripts expressed in adipose tissue and fetal liver, as well as adipose stromal cells in primary culture in the presence of dexamethasone and fetal calf serum (FCS). Identification of hormone-responsive, tissue-specific promoter regions, as well as growth factor-response elements upstream of exon 1.4, may provide insight into the regulation of estrogen biosynthesis in adipose tissue, which is implicated in the development of breast and endometrial cancer. The goals of the present study were to define the 1.4 promoter region with respect to the start of transcription and to characterize the region(s) responsible for conferring glucocorticoid responsiveness on aromatase expression. The transcription initiation site was identified by means of primer extension and S1 nuclease protection analyses. No TATA-like sequence was evident upstream of this site. Various deletion mutations of the upstream flanking region of exon 1.4 and including part of exon 1.4 were made using polymerase chain reaction or restriction enzyme digestion. The genomic fragments were fused upstream of the chloramphenicol acetyltransferase (CAT) reporter gene. These constructs were transfected into adipose stromal cells and fetal hepatocytes in primary culture in medium containing FCS with or without dexamethasone. The -560/+10 base pair (bp) construct expressed CAT activity after a putative silencer element was deleted, and expression was induced by dexamethasone about 3-fold. Transfection of the -330/+170 bp construct, which contains an upstream glucocorticoid response element (GRE) as well as an Sp1-like sequence in untranslated exon 1.4, resulted in an 8-fold stimulation of expression of CAT activity by dexamethasone. The upstream GRE as well as the Sp1-like sequence in untranslated exon 1.4 were mutated separately, and together, to further confirm whether the GRE or Sp1 binding site play a role in the regulation of promoter 1.4-driven transcription. Mutation of either the GRE or Sp1 binding site, or both, in the -330/+170 bp construct, resulted in loss of dexamethasone-induced CAT reporter gene expression.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of the sequences of the human CYP19 (aromatase) gene that mediate regulation by glucocorticoids in adipose stromal cells and fetal hepatocytes. 777 80

Estrogens are synthesized from C19 steroids by a unique form of cytochrome P450, aromatase cytochrome P-450 (P-450AROM; the product of the CYP19 gene). We have shown that tissue-specific expression of human P-450AROM is determined, in part, by the use of alternative promoters. Previous methods of analysis for determining the specific 5'-termini of the different transcripts included S1 nuclease protection, primer extension, and Northern analysis. In the present study we have used the RACE procedure (rapid amplification of cDNA ends) to amplify and clone the 5' termini of P-450AROM transcripts expressed in human corpus luteum (CL). Sequencing of the resulting clones supports the results of the previously performed studies. Specifically, the proximal promoter, PII, is the predominant promoter utilized in CL, such that the start of transcription occurs 26 bp downstream of the putative TATA sequence. A minority of the clones possess an alternative 5'-end, namely I.3. Exon-specific Northern analysis confirms that the majority of the P-450AROM transcripts in CL tissue contain sequence specific for promoter II. Similarly, exon-specific Northern analysis indicates that transcripts in human follicles, as well as granulosa cells in culture, contain primarily sequence specific for promoter II.
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PMID:Exon-specific northern analysis and rapid amplification of cDNA ends (RACE) reveal that the proximal promoter II (PII) is responsible for aromatase cytochrome P450 (CYP19) expression in human ovary. 814 90