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)

Hormonal regulation of mouse mammary tumor virus (MMTV) synthesis was studied in the CCL-51-SF cell subline derived from the Sykes' mammary tumor cell line CCL-51 and adapted to grow in semi-synthetic in vitro conditions. The virus was quantitated by measuring the supernatant reverse transcriptase activity in exogenous reaction using poly (rA)-oligo (dT) and poly (rC)-oligo (dG) as template/primers. The cells produced a low but significant amount of virus in the absence of any hormones and serum proteins. The synthetic glucocorticoid dexamethasone increased production considerably, up to 100-fold. Pretreatment of CCL-51-SF cells with serum or 5-bromodeoxyuridine, BrdUrd, partly reduced the stimulation by dexamethasone of MMTV production. Insulin and prolactin alone or in combination had no stimulating effect on spontaneous MMTV synthesis and cell growth. Prolactin, and more efficiently the prolactin-insulin combination, enhanced the MMTV production stumulated with dexamethasone. Insulin alone remained without effect. The polyamine spermidine, but not spermine, increased the MMTV production over the control by a factor of 2. Polyamines did not influence cell replication at the concentrations used.
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PMID:Mouse mammary tumor virus production stimulated by hormones and polyamines in cells grown in semi-synthetic in vitro conditions. 6 40

Prolactin mRNA has been isolated using immunochemical techniques. Initial experiments demonstrated that 125I-labeled prolactin antibody was able to bind to pituitary polysomes but not to liver polysomes, suggesting that the binding is specific. Prolactin-synthesizing polysomes were immunoprecipitated by reaction with antiprolactin followed by anti-antibody. Immunoprecipitated polysomal RNA was chromatographed on oligo(dT)-cellulose, and the poly(A) RNA was sedimented through a sucrose gradient. This procedure resulted in a 320-fold purification of prolactin mRNA as determined by translation in a mRNA-dependent reticulocyte lysate assay. Translation analysis also suggested that the isolated prolactin mRNA is greater than 95% pure. The molecular weight of prolactin mRNA determined by electrophoresis on agarose gels containing 10 mM mercury hydroxide was 350,000. Purified prolactin mRNA was used to synthesize full-length cDNA by means of avian myeloblastosis reverse transcriptase. Use of this cDNA as a hybridization probe demonstrated that estrogen is able to increase the concentration of prolactin mRNA sequences in the pituitary.
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PMID:Immunochemical isolation of prolactin messenger RNA. 735 64

Prolactin (PRL) is involved in a wide range of physiological effects in several species and its immunoregulatory role has already been well documented. The PRL receptor has been cloned from various species. There are at least two receptor isoforms (short and long) in rats and mice, which differ only in their cytoplasmic domains, generated by alternative splicing of a single gene, although in human only the long form exists. Using the reverse transcriptase-polymerase chain reaction (RT-PCR), we detected transcripts encoding both forms of PRL receptor in all lymphoid tissues examined in human, mouse, and rat, but in mouse and rat the ratio between the two forms was variable from animal to animal. Concerning the transcript encoding the PRL itself, a clear signal was always found in human lymphocytes and occasionally in rat thymus. We also developed a quantitative PCR (Q-PCR) in order to measure the absolute number of transcripts in thymus and spleen from rats at two stages of estrous cycle. The level of expression of the two forms was about equal. Finally, we identified the tyrosine kinase JAK2, which is constitutively associated with the PRLR, using the Nb2 rat lymphoma cell line as a model system with which to study the action of PRL on cell mitogenesis. We also showed that, after stimulation by PRL, the dimerization process is a prerequisite step for the phosphorylation of the PRLR and JAK2, which represents the earliest event in the signal transduction pathway.
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PMID:Prolactin and the immune system. 784 46

Prolactin is a member of the growth hormone family and is required for the growth and terminal differentiation of the mammary gland. Ectopic production of this hormone has been reported in several species, including rat, sheep, goat and human mammary tissues. In this study, mouse mammary cell lines, xenographs in the mammary gland from these cell lines and from hyperplastic alveolar nodules, spontaneous tumours, and normal tissues were studied for de novo production of this growth factor. Prolactin transcripts were found by reverse transcriptase PCR in some neoplastic and preneoplastic tissues and in mouse mammary cell lines, NOG8 and CDNR4, but were not detected in the normal mouse mammary gland. Northern analysis revealed a 1 kb transcript for both cell lines that co-migrated with the prolactin pituitary transcript. Conditioned medium from NOG8 cells was positive for prolactin bioactivity by the Nb2 rat lymphoma cell proliferation assay, and Western analysis revealed the presence of immunoreactive proteins at M(r) 14,000 and 60,000. Prolactin-like bioactivity was not detected in conditioned medium from CDNR4 cells, but an immunoreactive protein of M(r) 60,000 was detected by Western analysis. The mouse mammary cell line, Comma D, was negative for prolactin transcripts; however, adenocarcinomas derived from inoculation of Comma D cells into the cleared mammary fat pad were positive by reverse transcriptase PCR in two of four cases. Hyperplastic outgrowths maintained in the cleared mammary fat pad as well as spontaneous tumors were positive for prolactin transcripts in one of four cases. These results suggest that prolactin can be produced ectopically by the neoplastic mouse mammary gland.
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PMID:Expression of a prolactin-like factor in preneoplastic and neoplastic mouse mammary gland and cells. 898 Dec 31

The regulation of human implantation is still unknown. Evidence from mice suggests an essential role for several paracrine mediators but species differences with implantation in the human preclude the extrapolation of these concepts to humans. An intrauterine microdialysis device (IUMD), consisting of microdialysis tubing glued into a balloon catheter on one side and into a polypropylene tube on the other, allows a dynamic and accurate in-vivo measurement of uterine paracrine interactions in humans. Inserted into the uterine cavity in the form of a loop, it can be continuously perfused with saline to reveal a number of relevant cytokines and growth factors in uterine effluents of non-pregnant women in both follicular and luteal phases. These included interleukin (IL)-1alpha, IL-1beta, IL-6, leukaemia inhibitory factor (LIF), macrophage colony-stimulating factor (M-CSF), epidermal growth factor, vascular endothelial growth factor (VEGF), insulin-like growth factor binding protein-1 (IGFBP-1), prolactin, and human chorionic gonadotrophin (HCG). The source of intrauterine HCG is unclear since endometrial mRNA for the HCG beta-subunit is not revealed using reverse transcriptase polymerase chain reaction analysis. Applying urinary HCG locally via the IUMD profoundly alters endometrial secretory parameters. Prolactin, IGFBP-1, and M-CSF are significantly inhibited and VEGF is regulated in a biphasic manner involving early stimulation followed by inhibition of intrauterine levels. Use of the IUMD has thus shown that the urinary HCG preparations routinely used for ovulation induction and luteal support may directly alter endometrial function.
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PMID:Novel insights into human endometrial paracrinology and embryo-maternal communication by intrauterine microdialysis. 1002 6

Prolactin is mainly known for its role in breast development and lactation, but has been also implicated in other physiological functions such as immunoregulation and ovarian steroid production. Although prolactin and prolactin receptor (PRL-R) transcripts have been previously identified in the human ovary, the spatial localization of the receptor is unknown. To investigate the presence of PRL-R within the follicular apparatus, human luteinized granulosa cells were obtained at the time of follicular aspiration from women undergoing ovarian stimulation for IVF. RNA extracted from these cells was subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) using specific primers for the PRL-R gene. In addition, paraffin sections of isolated granulosa cells and sections of premenopausal human ovaries were immunostained with a mouse anti-human PRL-R monoclonal antibody. PRL-R were immunolocalized to the cell membrane of isolated luteinized granulosa cells and PRL-R transcripts were detected in the extracted RNA. No detectable staining was noted in secondary and early antral follicles in archived paraffin sections. These findings confirm the presence of PRL-R in human luteinized granulosa cells and suggest a localized role for PRL within the mature follicle. The absence of PRL-R in the early follicle suggests that the effects of prolactin are exerted around the time of ovulation.
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PMID:Prolactin receptor gene expression and immunolocalization of the prolactin receptor in human luteinized granulosa cells. 1167 69

The prolactin family represents a group of hormones and cytokines that participate in the control of maternal and fetal adaptations to pregnancy. The aim of this study was to develop a simple assay for monitoring patterns of prolactin family gene expression in rats and mice. Prolactin family cDNAs were spotted on to nylon membranes. Total RNA was extracted from tissues or cells. cDNAs were generated, radiolabelled using reverse transcriptase, and used as probes to hybridize with the prolactin family miniarrays. Pituitary, uterine decidual tissue and placenta each expressed a unique profile of prolactin family members. Placental tissues exhibited regional- and temporal-specific patterns of expression. Prolactin family gene expression differed markedly in mid-pregnant versus late gestation placental tissues and between the junctional and labyrinthine zones of the chorioallantoic placenta. Marked changes in prolactin family gene expression were also observed in cultured trophoblast cells undergoing differentiation. In conclusion, the prolactin family miniarray assay is an effective method for evaluating the endocrine phenotype of the uterus, placenta and trophoblast cells.
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PMID:Prolactin family miniarray: a tool for evaluating uteroplacental-trophoblast endocrine cell phenotypes. 1253 Sep 13

Prolactin (PRL) secretion is regulated by both inhibitory and stimulatory factors. Dopamine is the primary inhibitor, but multiple factors stimulate PRL gene expression and release. These can be divided into two categories: those that rapidly stimulate PRL release and those that induce the PRL gene followed by increased release. The pituitary intermediate lobe (IL) contains a PRL-releasing factor (PRF) that rapidly stimulates PRL release. From a mouse IL tumor, we established a non-melanotroph cell line, mIL5, which secretes a factor that stimulated PRL gene expression and release in vitro. This PRF activity did not rapidly stimulate PRL release and bound to heparin. Our objective was to examine the regulation of PRL by heparin-binding proteins and characterize the PRF activity produced by mIL5 cells. PRL gene expression and release was determined using GH3 cells, stably transfected with a PRL promoter/luciferase reporter (GH(3)/luc). After screening mIL5 cells by reverse transcriptase polymerase chain reaction, we found that they expressed two heparin-binding growth factors basic fibroblast growth factor (FGF-2) and heparin-binding epidermal growth factor (HB-EGF) which were considered strong candidates for PRL transcriptional regulatory activity. To determine whether the activity produced by mIL5 cells is attributed to FGF-2 or HB-EGF, three approaches were used: heparin-affinity chromatography, Western blotting, and immunoneutralization. The PRF activity in conditioned media eluted from heparin with 1 M NaCl whereas both FGF- 2 and HB-EGF eluted with >1 M NaCl. Neither growth factor was detectable in mIL5 cells by Western blotting. Antibodies directed against FGF-2 and HB-EGF, alone or together, did not abolish this activity from mIL5 cells. In conclusion, FGF-2 and HB-EGF are potent stimulators of PRL gene expression and release but do not account for most of the endogenous PRL gene activity in mIL5 cells. The distinct heparin-binding factor that stimulates PRL gene transcription remains to be identified.
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PMID:Prolactin regulation by heparin-binding growth factors expressed in mouse pituitary cell lines. 1266 66

Prolactin (PRL) is a single-chain polypeptide hormone that is generally secreted from prolactin cells of the anterior pituitary gland into the blood circulation. However, recent studies indicate that the gene expression of prolactin is ectopic in several tissues across several species. These studies found that lymphocytes also produce PRL, which is involved in the immunoregulatory system. Here, we searched for PRL messenger ribonucleic acid (mRNA), using the reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blotting in the spleens of mice at various growth stages. We also localized mouse prolactin (mPRL) and its mRNA in the spleens of 30- and 60-day-old mice by immunohistochemistry and in situ hybridization respectively. The mPRL gene was expressed in all spleen samples at 0-60 days postpartum. We localized mPRL mRNA in the sheathed artery, periarterial lymphatic sheath and the marginal zone of the spleen. Moreover, we detected mPRL in essentially the same area as its mRNA. Furthermore, we performed double-fluorescence immunohistochemical staining for mPRL and mouse CD4 that is specifically produced in helper T cells, or for mPRL and mouse CD19 or CD40 specified B cells. We colocalized mPRL immunoreactivity only in some CD4-immunopositive cells. These results clearly suggest that T cells synthesize mPRL in the mouse spleen.
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PMID:Prolactin gene expression in mouse spleen helper T cells. 1559 Sep 89

Prolactin releasing peptide (PrRP) is a neuropeptide with 31 or 20 amino acid residues and regarded as a potent and specific stimulator of pituitary prolactin. PrRP immunoreactive (PrRP-ir) neurons and mRNA are found in medulla oblongata and hypothalamus and the fibers containing PrRP are widely distributed in rat brains. Therefore, it is postulated that PrRP might act as a neurohormone or a neurotransmitter as well as a neuromodulator in the brain. In the present study, we probed the expression of brain PrRP in the estrous cycle of female rats and the relationship between brain PrRP and GnRH. Female rats were divided into four groups: the diestrus, the proestrus, the estrus and the metaestrus, which were identified by the vaginal cytological examination. Immunohistochemistry, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescent double labeling histochemistry combining confocal laser scanning microscope (CLSM) were used. The results showed that PrRP immunoreactive neurons in nucleus of solitary tract (NTS) and ventrolateral reticular nucleus (VLRN) in the proestrus were less than those in the diestrus, the estrus and the metaestrus. Similarly, the relative optical density of PrRP-ir fibers of the bed nucleus of stria terminalis (BST) in the proestrus was decreased compared with those in other three groups. However, the brain PrRPmRNA level was higher in the proestrus and estrus than those in the metaestrus and diestrus. We also observed the co-localization of GPR10-immunoreactive (GPR10-ir) and GnRH-immunoreactive (GnRH-ir) neurons in hypothalamic medial preoptic area (MPO). The present results provide morphological evidences that PrRP in the female rat brains might participate in the regulation of the rat estrous cycle at least in a direct way.
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PMID:Expression of brain prolactin releasing peptide (PrRP) changes in the estrous cycle of female rats. 1747 3


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