Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of occult malignancies in breast cancer patients is evolving as a useful diagnostic tool. However, no reliable molecular mRNA markers are available. We developed an RT-PCR plus Southern blot assay using beta-hCG (beta-subunit of human chorionic gonadotropin) gene expression as a tumor marker for detection of breast malignancies metastatic to tumor-draining lymph nodes and blood. Breast carcinoma cell lines, primary breast malignancies and human placenta were used as positive controls for establishing the beta-hCG RT-PCR assay. Peripheral blood leukocytes (PBL) from normal volunteer donors, normal breast tissue and lymph nodes from cancer-free patients were used as negative controls. beta-hCG RT-PCR was used to assess tumor cell presence in PBL and tumor-draining axillary nodes from patients with AJCC stage I-IV breast cancer. The assay sensitivity and specificity were enhanced by restriction endonuclease digestion of an Sty I site of the RT-PCR cDNA product followed by Southern blot analysis. beta-hCG mRNA was expressed in all breast cancer cell lines and 80% of primary breast cancers; it was not expressed in negative controls. The assay reliably detected one cancer cell in > 10(7) PBL, with a sensitivity of 10(-5) microgram RNA. Eighty percent of PBL and 61% of tumor-draining axillary nodes from breast cancer patients expressed beta-hCG mRNA. The assay is a sensitive and specific method of identifying breast cancer cells in breast tissues, lymph nodes and blood.
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PMID:Detection of metastatic breast cancer by beta-hCG polymerase chain reaction. 890 Mar 69

In order to study salmon thyroid-stimulating hormone (TSH), we designed a highly specific, sensitive, and rapid RNase protection assay (RPA) for quantification of steady-state levels of salmon TSH beta-subunit mRNA expression. The cDNA encoding the beta-subunit of TSH was isolated from coho salmon pituitary total RNA by reverse-transcriptase PCR, partially sequenced, and used as template for synthesizing a radioactively labeled, sequence-specific, antisense probe, and sense standard for the RPA. This assay, along with a similar RPA previously designed for coho salmon total alpha-subunit mRNA, was used to examine the effects of feeding T3 (0, 10, 100 micrograms/g) and methimazole (a thyroid inhibitor) (2.5 mg/g) on TSH subunit gene expression after 2 and 4 weeks. The low dose of T3 (10 micrograms/g) caused no change in TSH beta mRNA after 2 and 4 weeks and a transient increase in alpha mRNA after 2 weeks, followed by no significant effect after 4 weeks. The high dose of T3 (100 micrograms/g) caused a decrease in TSH beta mRNA after 4 weeks and no change in total alpha mRNA after 2 and 4 weeks. In contrast, methimazole treatment caused significant increases in both TSH beta mRNA (250%) and alpha mRNA (50%) levels after 4 weeks. These findings confirm that, as in mammals, TSH alpha- and beta-subunit expression in teleosts may be differentially regulated by negative feedback from the thyroid hormones.
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PMID:Quantification of salmon alpha- and thyrotropin (TSH) beta-subunit messenger RNA by an RNase protection assay: regulation by thyroid hormones. 920 9

The confounding problem in treatment of breast cancer is the metastasis of breast tumour. Reverse transcriptase polymerase chain reaction (RT-PCR) has been recently used in the detection of circulating breast cancer cells. This review reports on the development of this assay as well as its advantages and disadvantages. We feel that cytokeratin 20 and beta -human chorionic gonadotropin (hCG) mRNA are the best markers for the detection of circulating breast cancer cells. We suggest that the multiple RNA marker RT-PCR assay can help to increase both sensitivity and specificity of detection, and that quantitative RT-PCR assay is more effective than the qualitative assay in the detection of circulating breast cancer cells.
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PMID:Detection of circulating breast cancer cells by reverse transcriptase polymerase chain reaction (RT-PCR). 1103 1

Ectopic production of biologically active glycoprotein hormones other than hCG has been reported in exceptional cases. A 61-yr-old man came to our Unit complaining of weakness, fatigue and reduced libido with erectile dysfunction. There was also a history of polycythemia, known for about 10 yr and never further investigated. The physical examination showed acne and redness of facial skin and upper chest; no other significant abnormalities were detected. Serum levels of LH were very high, whereas alpha-subunit and hCG were only slightly increased. Testosterone and 17beta-estradiol levels were increased too. Abdominal computed tomography (CT) scan revealed a large hypervascularized mass within the pancreatic tail, which was surgically removed by distal splenopancreatectomy. Diffuse immunoreactivity for LH was detected in more than 70% of the tumor cells. The alpha-subunit was also positive, while chorionic gonadotropin had only a focal reactivity. Reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern Blot analysis confirmed the synthesis of LH by the tumor. Four weeks after surgery, serum levels of LH, alpha-subunit, testosterone, hCG and 17beta-estradiol were all undetectable. The redness of facial skin and upper chest had disappeared, but libido was still reduced. At a further control, 3 months after surgery, serum levels of LH, FSH, hCG, alpha-subunit and 17beta-estradiol were all within the normal range, as well as hemoglobin concentration and the red blood cells count. Testosterone was slightly below normal, but the patient reported an increase of libido. This is an unusual case of ectopic secretion of LH from an endocrine tumor of the pancreas.
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PMID:Ectopic secretion of LH by an endocrine pancreatic tumor. 1523 57

Activation of the luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor (LHR) in cultured hypothalamic cells and immortalized GnRH (gonadotropin-releasing hormone) neurons (GT1-7 cells) transiently stimulates and subsequently inhibits cAMP production and pulsatile GnRH release. The marked and delayed impairment of cAMP signaling and episodic GnRH release in GT1-7 cells is prevented by pertussis toxin (PTX). This, and the LH-induced release of membrane-bound Galpha(s) and Galpha(i3) subunits, are indicative of differential G protein coupling to the LHR. Action potential (AP) firing in identified GnRH neurons also initially increased and then progressively decreased during LH treatment. The inhibitory action of LH on AP firing was also prevented by PTX. Reverse transcriptase-PCR analysis of GT1-7 neurons revealed the expression of G protein-gated inwardly rectifying potassium (GIRK) channels in these cells. The LH-induced currents were inhibited by PTX and were identified as GIRK currents. These responses indicate that agonist stimulation of endogenous LHR expressed in GnRH neurons activates GIRK channels, leading to suppression of membrane excitability and inhibition of AP firing. These findings demonstrate that regulation of GIRK channel function is a dominant factor in gonadotropin-induced abolition of pulsatile GnRH release. Furthermore, this mechanism could contribute to the suppression of pituitary function during pregnancy.
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PMID:Essential role of G protein-gated inwardly rectifying potassium channels in gonadotropin-induced regulation of GnRH neuronal firing and pulsatile neurosecretion. 1682 87

Luteinizing hormone (LH) influences the secretion of melatonin (N-acetyl-5-methoxytryptamine) from the pineal gland. The present study examined the possible presence of LH/chorionic gonadotropin (CG) receptor in the pineal gland of adult female rats. Reverse transcriptase-polymerase chain reaction analyses demonstrated that LH/CG receptor mRNA is expressed in the pineal gland. Western blotting showed that the pineal gland, like the ovary, contains an 80 kDa receptor protein. Immunohistochemistry revealed that LH/CG receptor, arylalkylamine N-acetyltransferase (a regulatory enzyme in melatonin biosynthesis) and serotonin (a melatonin precursor) are localized primarily to the same cells of the pineal gland. We further found that the levels of pineal LH/CG receptor protein in normal cycling female rats change significantly during the estrous cycle, being lowest at early metestrus. These results demonstrate that LH/CG receptor is expressed in the pineal gland, primarily in melatonin-synthesizing cells, namely pinealocytes. Furthermore, it is suggested that LH influences pineal melatonin secretion through binding to this receptor. In addition, LH/CG receptor levels in the pineal gland are regulated during the estrous cycle under normal physiological conditions.
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PMID:Expression of luteinizing hormone/chorionic gonadotropin receptor in the rat pineal gland. 1684 39

Luteinizing hormone (LH) and human chorionic gonadotropin (hCG) play an important role in the development and maintenance of male and female gonads. Both these hormones act through the same specific receptor LH/hCG receptor (LHR). Recent studies have shown the existence of functional LHR in several non-gonadal tissues. The aim of this study was to confirm the functional existence of LHR in an endometrial adenocarcinoma cell line, Ishikawa cells, which has been used since long as an in vitro uterine endometrium model. Reverse transcriptase-polymerase chain reaction (RT-PCR) data showed the stable expression of LHR in this cell line. However, the receptor failed to activate the PKA pathway in response to hCG, which is the most conventional mode of LH/hCG action in target tissues. When tested for other pathways, hCG failed to activate them either. Nested RT-PCR confirmed the existence of full-length LHR and this was further supported by Western blot. This study demonstrated that although Ishikawa cells do possess a full-length LHR, which was confirmed by RT-PCR, nested RT-PCR, Western blot and DNA sequencing, it failed to activate the conventional LH-mediated downstream signaling. Based on these data we hypothesize that in Ishikawa cells LH/hCG does not utilize its conventional receptor. Whether it acts through some other receptor is a question, which can be answered through future research.
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PMID:Assessment of luteinizing hormone receptor function in an endometrial cancer cell line, Ishikawa cells in response to human chorionic gonadotrophin (hCG). 1754 47

Piwi proteins are required for germline maintenance and gonad development. In this study, the cDNAs encoding Piwil1 and Piwil2 were cloned and sequenced from the common carp. The full-length cDNA of Piwil1 and Piwil2 were 3114 and 3421bp, encoding 858 and 1034 amino acids including PAZ domain and PIWI domain, respectively. In addition, the Piwil1 and Piwil2 proteins shared high homology with other teleosts. Reverse transcriptase PCR revealed that the Piwi mRNAs were exclusively expressed in adult testes and ovaries. Using real-time PCR, expression study of different developmental profiles showed that Piwil1 and Piwil2 were down-regulated during pre-ovulation. Further, human chorionic gonadotropin treatment in ovaries (in vivo) and in cultured ovaries cells (in vitro) resulted in down-regulation of Piwi RNAs. These results suggest that the decreased expression which was regulated by hormone plays a crucial role during ovarian differentiation and development.
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PMID:Human chorionic gonadotropin suppresses expression of Piwis in common carp (Cyprinus carpio) ovaries. 2233 51

In mouse ovarian follicles, the oocyte is maintained in meiotic prophase arrest by natriuretic peptide type C (NPPC) acting via its cognate receptor, natriuretic peptide receptor 2 (NPR2). As there is a marked species difference in the receptor selectivity of the natriuretic peptide family, this study examined the functional effect of other natriuretic peptides, type A (NPPA) and type B (NPPB), acting via NPR2 on mouse-oocyte meiotic arrest. The results by quantitative, reverse-transcriptase PCR showed that Npr2 was the predominant natriuretic peptide receptor transcript, and that Npr1 and Npr3 mRNA levels were negligible in cumulus cells isolated from equine chorionic gonadotropin (eCG)-primed, immature female mice. While NPPA and NPPB from human and rat had no effect on oocyte maturation, porcine NPPB (pNPPB) maintained oocyte meiotic arrest in a dose-dependent manner. Furthermore, pNPPB-mediated meiotic arrest and cGMP production could be completely blocked by the NPR2 inhibitor sphingosine-1-phosphate (S1P). Neither the NPR1 antagonist anantin or Npr1 knockout had an effect on pNPPB-mediated meiotic arrest. Thus, pNPPB can functionally maintain mouse-oocyte meiotic arrest by the receptor NPR2 of cumulus cells. These findings demonstrate that pNPPB may be used as a probe to identify the essential amino acid sequences for activation of NPR2.
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PMID:Porcine natriuretic peptide type B (pNPPB) maintains mouse oocyte meiotic arrest via natriuretic peptide receptor 2 (NPR2) in cumulus cells. 2461 55