Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Steroidogenic acute regulatory (StAR) protein mediates the rapid increase in steroid hormone biosynthesis in response to tropic hormones by facilitating transport of cholesterol into the inner mitochondrial membrane. Although our laboratory has recently reported on the hormonal regulation of StAR mRNA in the rat ovary, the same regulation in the human corpus luteum requires analysis. To this end, a human StAR complementary DNA (cDNA) probe of 858 bp was generated using reverse transcriptase-PCR and RNA from human corpora lutea. The StAR sequence was confirmed by dideoxy chain-termination sequence analysis. Northern blot analysis using the StAR cDNA probe on human corpora lutea mRNA showed that the probe hybridized to a major 1.6-kb transcript and a minor 4.4-kb transcript. Examination of corpora lutea of different luteal phases revealed that the basal expression of the 1.6-kb transcript was significantly more abundant in the early (days 15-19) luteal phase than in the middle (days 20-23) or late (days 24-28) phases. To examine the hormonal regulation of StAR mRNA, corpora lutea were treated in vitro with increasing concentrations of human chorionic gonadotropin (hCG) or prostaglandin F2 alpha (PGF2 alpha). Following hCG stimulation, both 1.6- and 4.4-kb StAR transcripts were increased. A statistically significant increase of 2.2- and 1.8-fold in the 1.6-kb transcript was seen with hCG concentrations of 50 and 100 mIU/mL, respectively. This increase was coupled with a significant elevation in media progesterone levels. In contrast, PGF2 alpha treatment significantly decreased both StAR messenger ribonucleic acid (mRNA) expression and media progesterone levels at concentrations of 500 and 5000 ng/mL. This investigation demonstrated that StAR mRNA is regulated by tropic hormones and prostaglandins in the human corpus luteum. The parallel change in StAR mRNA in conjunction with a change in progesterone levels further supports StAR's putative role in the regulation of steroidogenesis.
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PMID:Hormone and prostaglandin F2 alpha regulation of messenger ribonucleic acid encoding steroidogenic acute regulatory protein in human corpora lutea. 970 72

Using a mouse Leydig tumor cell line, we explored the mechanisms involved in thyroid hormone-induced steroidogenic acute regulatory (StAR) protein gene expression, and steroidogenesis. Triiodothyronine (T3) induced a approximately 3.6-fold increase in the steady-state level of StAR mRNA which paralleled with those of the acute steroid response ( approximately 4.0-fold), as monitored by quantitative reverse transcriptase-polymerase chain reaction assay and progesterone production, respectively. The T3-stimulated progesterone production was effectively inhibited by actinomycin-D or cycloheximide, indicating the requirement of on-going mRNA and protein synthesis. T3 displayed the highest affinity of [125I]iodo-T3 binding and was most potent in stimulating StAR mRNA expression. In accordance, T3 significantly increased testosterone production in primary cultures of adult mouse Leydig cells. The T3 and human chorionic gonadotropin (hCG) effects on StAR expression were similar in magnitude and additive. Cells expressing steroidogenic factor 1 (SF-1) showed marginal elevation of StAR expression, but coordinately increased T3-induced StAR mRNA expression and progesterone levels. In contrast, overexpression of DAX-1 markedly diminished the SF-1 mRNA expression, and concomitantly abolished T3-mediated responses. Noteworthy, T3 augmented the SF-1 mRNA expression while inhibition of the latter by DAX-1 strongly impaired T3 action. Northern hybridization analysis revealed four StAR transcripts which increased 3-6-fold following T3 stimulation. These observations clearly identified a regulatory cascade of thyroid hormone-stimulated StAR expression and steroidogenesis that provides novel insight into the importance of a thyroid-gonadal connection in the hormonal control of Leydig cell steroidogenesis.
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PMID:Molecular mechanisms of thyroid hormone-stimulated steroidogenesis in mouse leydig tumor cells. Involvement of the steroidogenic acute regulatory (StAR) protein. 1002 15

Membrane receptors for human chorionic gonadotropin (hCG) are expressed in a variety of steroidogenic cells, and also in extragonadal tissues such as vessels of the female genital tract. We examined the possible contribution of hCG to the endocrine control of prearteriolar mesenteric and uterine vessels before and during pregnancy. Lumen diameters of isolated pressurized resistance arteries from Sprague-Dawley rats were measured using a video-electronic system. hCG produced marked and dose-dependent vasodilation. Uterine radial arteries were found to be highly sensitive to hCG (EC50 approximately =60 mU/ml) before and throughout gestation. Second-order mesenteric arteries from nonpregnant animals were even more sensitive (EC50=38 mU/ml), but, in these vessels, responsiveness to hCG was significantly attenuated by the pregnant state. Mechanical removal of the vascular endothelium did not reduce the degree of vasodilation mediated by hCG. The expression of hCG receptor mRNA in intact vessels could be demonstrated using reverse transcriptase polymerase chain reaction (RT-PCR). hCG appears to be an important embryonic signal, which could trigger adaptive cardiovascular changes in early pregnancy, simultaneously preserving a sufficient utero-placental perfusion during the entire gestation period by an endothelium-independent mechanism.
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PMID:Human chorionic gonadotropin dilates uterine and mesenteric resistance arteries in pregnant and nonpregnant rats. 1065 Oct 16

Previously, we reported that the expression of keratinocyte growth factor (KGF) is enhanced in secretory phase endometrial and decidual cells in early pregnancy as compared with the expression of KGF in proliferative phase endometrial cells, in humans. In order to clarify the role of KGF in embryo-endometrial interaction, we analyzed the in vitro effect of KGF on the human chorionic gonadotropin (hCG) secretion and on DNA synthesis in chorionic villi which are in close contact with the endometrium/decidua in the early stage of pregnancy. In this study, we used the BeWo cell line, a human choriocarcinoma cell line that possesses the biological features of secreting various placental hormones including hCG. Furthermore, we investigated the expression of KGF receptor (KGF-R) in these cells. KGF significantly stimulated hCG secretion in cultured BeWo cells but did not affect [3H]-thymidine incorporation. KGF-R mRNA was detected in BeWo cells by reverse transcriptase-polymerase chain reaction. These results suggest that the expression of KGF, which is induced in endometrial/decidual cells by progesterone, plays an important role in the embryo-endometrial/ decidual interaction by stimulating hCG secretion rather than affecting cell proliferation.
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PMID:Biological action of keratinocyte growth factor in BeWo cells, a human choriocarcinoma cell line. 1069 46

In a preview study we found that luteinizing granulosa cells from follicles of patients with polycystic ovary syndrome (PCOS) have a reduced capacity to synthesize progesterone in vitro. Because the 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) is an important enzyme for the biosynthesis of progesterone, the reduced capacity of PCO luteinizing granulosa cells to synthesize progesterone in vitro may be due to reduced 3 beta-HSD gene expression. A reverse transcriptase polymerase chain reaction for 3 beta-HSD was performed and the relative intensity of signals for 3 beta-HSD was evaluated using computer-assisted densitometry. Cells from polycystic ovaries expressed less 3 beta-HSD in follicles < or 10 mm (p < 0.05) and in follicles > or 16 mm (p < 0.05) than cells from normal ovaries. Furthermore, after human chorionic gonadotropin stimulus (50 ng/ml), cells from polycystic ovaries expressed less 3 beta-HSD in follicles > or = 16 mm (p < 0.01) than cells from normal ovaries. The data show that there is a specific change in the gene expression of 3 beta-HSD in PCO granulosa cells resulting in a suppressed capacity to secrete progesterone.
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PMID:Polycystic ovary syndrome: evidence for reduced 3 beta-hydroxysteroid dehydrogenase gene expression in human luteinizing granulosa cells. 1081 4

Some pituitary hormones are expressed in leukocytes and are thought to play a role in the regulation of leukocyte function. We studied the expression of the mRNA for the beta-chains of luteinising hormone (LHbeta) and chorionic gonadotropin (CGbeta) and their translation into protein in various leukocyte subsets. Monocytes, granulocytes, B and T-cells from peripheral blood were separated. Lymphocytes were stimulated with various mitogens, prolactin and mixed lymphocyte culture. LHbeta and CGbeta mRNA expression was determined by reverse transcriptase polymerase chain reaction. LH, LHbeta, CG and CGbeta protein were determined in the culture medium by immunofluorometric assays. LHbeta mRNA expression was detected in all cell fractions and cultures and stimulation with prolactin induced LH protein in the culture medium. CGbeta mRNA expression appeared after culture of lymphocytes, but mitogens and prolactin had no clear stimulating effect. The LH expression in leukocytes shown here suggests an autocrine function of this hormone in blood cells.
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PMID:Expression of luteinising hormone and chorionic gonadotropin beta-subunit messenger-RNA and protein in human peripheral blood leukocytes. 1085

We describe a reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of human chorionic gonadotropin-beta (HCG beta) mRNA copies using the TaqMan system. To evaluate our quantitative assay, we analyzed HCG beta transcripts of all protein coding genes (HCG beta 5, 3, 8, and 7) in human RNA panels of different normal tissues and in glycodelin-A-stimulated trophoblast cell cultures. Absolute quantification using HCG beta TaqMan probe was found to be highly reproducible. Our study of RNA panels confirms recently published results that expression of HCG beta transcripts is a common feature of a great variety of different normal tissues. High levels of HCG beta mRNAs (> 1,000 molecules per 200 ng RNA) were detected in placenta, uterus, and testis. An increase of HCG beta mRNA expression (1.7-fold) was detected at 150 micrograms/mL glycodelin-A treatment in trophoblast cell culture. Time-dependence study showed that the increase in HCG beta mRNA level was evident at 60 min after glycodelin-A treatment. In summary, we have developed a highly sensitive one-tube, one-enzyme quantitative RT-PCR system that is time-saving and avoids postamplification procedures.
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PMID:Absolute quantification of human chorionic gonadotropin-beta mRNA with TaqMan detection. 4. 1091 14

We attempted to identify the cells expressing alpha and beta subunits of human chorionic gonadotropin (hCG) in the peripheral blood of patients with trophoblastic disease and normal pregnant women by using reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot. By this method, the mRNAs of hCG alpha and hCG beta were detected in the peripheral blood mononulear cells (PBMNC) from 3 of 7 hydatidiform mole (mole) and 1 of 4 choriocarcinoma patients as well as from normal pregnant women during the first trimester. None of the mRNAs of hCG subunits was detected in the PBMNC from healthy male and nonpregnant healthy women examined. The expression of hCG alpha and hCG beta in patients with trophoblastic disease and normal pregnant women almost correlated with their plasma levels of intact hCG. The present study indicates that the cells expressing hCG alpha and hCG beta, which virtually represent trophoblasts, are circulating in the peripheral blood of patients with trophoblastic disease as well as of normal pregnant women.
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PMID:Trophoblastic cells expressing human chorionic gonadotropin genes in peripheral blood of patients with trophoblastic disease. 1126 89

We have designed novel DNA primers that allow us to detect the expression of the subunits of chorionic gonadotropin (CG) from a variety of species of the order Primates. Using these primers, reverse transcriptase-polymerase chain reaction (RT-PCR), and standard cloning techniques, we detected the expression of a single gene for the common glycoprotein hormone (GPH) alpha-subunit and at least two genes for the CG beta-subunit in trophoblasts of Macaca fascicularis (cynomolgous macaque (cm)) at gestational day (GD) = 26 (+/- 2d). No cmCG expression was detected at GD = 35-40. When sequences of cmGPH-alpha and cmCG-beta genes were compared to the corresponding genes of other primates, we found that the alpha-subunit of M. fascicularis was highly conserved compared to other primate species. However, cmCG beta-subunits appeared to be less conserved, residing between those of human CG-beta and baboon CG-beta when analyzed phylogenetically. Of particular interest was a three amino acid stretch in one of the expressed cmCG-beta genes that is distinct from all other primates studied. Our findings imply that not only does the expression of multiple CG beta-subunit genes appear to be common to Old World monkeys, but that the presented methodology will greatly facilitate our ability to understand primate evolution.
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PMID:Comparison of chorionic gonadotropin expression in human and macaque (Macaca fascicularis) trophoblasts. 1179 16

The aim of this study was to use a two-marker assay for the detection of breast cancer cells circulating in patients' blood. We have applied a PCR-based methodology to follow up the possibility of the development of metastatic disease in stage I and II patients who had undergone curative surgery. Since the number of circulating cancer cells in peripheral blood is very low, the technique for their detection needs to be not only highly sensitive, but also very specific. The reverse transcriptase-polymerase chain reaction (RT-PCR) technique may improve the sensitivity of breast cancer cell detection up to only a few cells per one million. The principle of the RT-PCR assay is to amplify a messenger RNA characteristic for breast epithelial cells in a blood sample. Since we do not expect such cells to be circulating in peripheral blood of healthy subjects, detection of the characteristic mRNA should indicate the presence of circulating breast cancer cells. We analyzed the usefulness of three mRNA markers: cytokeratin 19 (CK19), mammaglobin (hMAM) and beta subunit of human chorionic gonadotropin (beta-hCG) for this test. Blood samples (112) were obtained from 55 patients, in stages I and II, with or without metastasis to regional lymph nodes (N0 or N1). We found that a two-marker assay increases the sensitivity of detection of breast cancer cells in comparison with a single-marker one. Combination of two tumor-specific mRNA markers, hMAM/CK19 or beta-hCG/CK19, allowed the detection of circulating breast cancer cells in 65% of N1 patients and 38% of N0 patients. By comparison, the combination hMAM/beta-hCG allowed the detection of circulating breast cancer cells in the blood of 68% of N1 patients and 46% of N0 patients. Addition of the third marker did not significantly increase the detection sensitivity.
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PMID:Detection of circulating breast cancer cells in peripheral blood by a two-marker reverse transcriptase-polymerase chain reaction assay. 1544 36


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