This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sun, T. Articles by Simpson, E. R. Search for Related Content PubMed PubMed Citation Articles by Sun, T. Articles by Simpson, E. R.

Characterization of a Region Upstream of Exon I.1 of the Human CYP19 (Aromatase) Gene That Mediates Regulation by Retinoids in Human Choriocarcinoma Cells

Cecil H. and Ida Green Center for Reproductive Biology Sciences (T.S., Y.Z., E.R.S.), Dallas, Texas 75235-9051; and the Departments of Obstetrics/Gynecology, Biochemistry (T.S., Y.Z., E.R.S.), and The Howard Hughes Medical Institute and Department of Pharmacology (D.J.M.), The University of Texas Southwestern Medical Center, Dallas, Texas 75235-9038

Address all correspondence and requests for reprints to: Tiejun Sun, M.D., Ph.D., Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75235-9038.

The biosynthesis of estrogens is catalyzed by aromatase P450 (P450_arom), 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 ovary, brain, adipose stromal cells, and placenta. Sequence corresponding to untranslated exon I.1 is present uniquely in 5'-termini of transcripts expressed in human placenta and choriocarcinoma cells, as a consequence of expression driven by a distal promoter, I.1. The goal of the present study was the identification of regulatory elements in this promoter region. Various deletion mutations of the upstream flanking region of exon I.1 were constructed using the PCR or restriction enzyme digestion. The genomic fragments were fused upstream of the luciferase reporter gene. These constructs were transfected into human choriocarcinoma (JEG3) cells. The longest construct employed, -924/+10 bp, expressed the highest luciferase reporter gene activity. The -64/+10 bp and -125/+10 bp constructs showed no reporter gene expression. Transfection of the -201/+10 bp construct resulted in reporter gene expression, but at a lower level than that of the -924/+10 bp construct, and this expression was induced by serum as well as by LG69 and TTNPB, ligands specific for RXR and RAR respectively, as well as by vitamin D. These results parallel the actions of the ligands on aromatase activity. Mutation or deletion of an imperfect palindromic sequence (AGGTCATGCCCC) located at -183 to -172 bp upstream of the transcriptional start site of exon I.1 resulted in loss of basal- and retinoid-induced reporter gene expression. Gel retardation analysis using nuclear extracts of JEG3 cells treated with retinoids and the imperfect palindromic sequence as probe, showed that proteins present in the nuclear extracts bound to this sequence in a specific fashion. The binding activities were elevated by incubation of the cells with LG69 and TTNPB, ligands specific for RXR and RAR respectively. Binding of nuclear proteins to the palindromic sequence was displaced either by anti-RXR serum or by anti-VDR serum, suggesting the formation of a heterodimer of RXR and VDR. These results suggest that the imperfect palindromic sequence upstream of exon I.1 plays an important but novel role in the regulated expression of the CYP19 gene in choriocarcinoma cells.

This article has been cited by other articles:

				T. Nakanishi, J.-i. Nishikawa, Y. Hiromori, H. Yokoyama, M. Koyanagi, S. Takasuga, J.-i. Ishizaki, M. Watanabe, S.-i. Isa, N. Utoguchi, et al. Trialkyltin Compounds Bind Retinoid X Receptor to Alter Human Placental Endocrine Functions Mol. Endocrinol., October 1, 2005; 19(10): 2502 - 2516. [Abstract] [Full Text] [PDF]

				S. J. Ellem, J. F. Schmitt, J. S. Pedersen, M. Frydenberg, and G. P. Risbridger Local Aromatase Expression in Human Prostate Is Altered in Malignancy J. Clin. Endocrinol. Metab., May 1, 2004; 89(5): 2434 - 2441. [Abstract] [Full Text] [PDF]

				A. Kovacic, C. J. Speed, E. R. Simpson, and C. D. Clyne Inhibition of Aromatase Transcription Via Promoter II by Short Heterodimer Partner in Human Preadipocytes Mol. Endocrinol., January 1, 2004; 18(1): 252 - 259. [Abstract] [Full Text] [PDF]

				Y. Kinoshita and S. Chen Induction of Aromatase (CYP19) Expression in Breast Cancer Cells through a Nongenomic Action of Estrogen Receptor {alpha} Cancer Res., July 1, 2003; 63(13): 3546 - 3555. [Abstract] [Full Text] [PDF]

				M. Huening, G. Yehia, C. A. Molina, and S. Christakos Evidence for a Regulatory Role of Inducible cAMP Early Repressor in Protein Kinase A-Mediated Enhancement of Vitamin D Receptor Expression and Modulation of Hormone Action Mol. Endocrinol., September 1, 2002; 16(9): 2052 - 2064. [Abstract] [Full Text] [PDF]

				G. L. Rubin, J. H. Duong, C. D. Clyne, C. J. Speed, Y. Murata, C. Gong, and E. R. Simpson Ligands for the Peroxisomal Proliferator-Activated Receptor {gamma} and the Retinoid X Receptor Inhibit Aromatase Cytochrome P450 (CYP19) Expression Mediated by Promoter II in Human Breast Adipose Endocrinology, August 1, 2002; 143(8): 2863 - 2871. [Abstract] [Full Text] [PDF]

				C. D. Clyne, C. J. Speed, J. Zhou, and E. R. Simpson Liver Receptor Homologue-1 (LRH-1) Regulates Expression of Aromatase in Preadipocytes J. Biol. Chem., May 31, 2002; 277(23): 20591 - 20597. [Abstract] [Full Text] [PDF]

				L. Blanchon, P. Sauvant, C. Bavik, D. Gallot, F. Charbonne, M.-C. Alexandre-Gouabau, D. Lemery, B. Jacquetin, B. Dastugue, S. Ward, et al. Human choriocarcinoma cell line JEG-3 produces and secretes active retinoids from retinol Mol. Hum. Reprod., May 1, 2002; 8(5): 485 - 493. [Abstract] [Full Text] [PDF]

				K. Kinuta, H. Tanaka, T. Moriwake, K. Aya, S. Kato, and Y. Seino Vitamin D Is an Important Factor in Estrogen Biosynthesis of Both Female and Male Gonads Endocrinology, April 1, 2000; 141(4): 1317 - 1324. [Abstract] [Full Text] [PDF]

				G. L. Rubin, Y. Zhao, A. M. Kalus, and E. R. Simpson Peroxisome Proliferator-activated Receptor {{gamma}} Ligands Inhibit Estrogen Biosynthesis in Human Breast Adipose Tissue: Possible Implications for Breast Cancer Therapy Cancer Res., March 1, 2000; 60(6): 1604 - 1608. [Abstract] [Full Text]

				K. Yamada, H. Ogawa, S.-i. Honda, N. Harada, and T. Okazaki A GCM Motif Protein Is Involved in Placenta-specific Expression of Human Aromatase Gene J. Biol. Chem., November 5, 1999; 274(45): 32279 - 32286. [Abstract] [Full Text] [PDF]

				A. Kamat, J. L. Alcorn, C. Kunczt, and C. R. Mendelson Characterization of the Regulatory Regions of the Human Aromatase (P450arom) Gene Involved in Placenta-Specific Expression Mol. Endocrinol., November 1, 1998; 12(11): 1764 - 1777. [Abstract] [Full Text]