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)

In the present study, we studied angiotensin II type 1 (AT1) and type 2 (AT2) receptor messengers by quantitative reverse transcriptase-polymerase chain reaction. We examined peripheral blood mononuclear cells from 30 healthy subjects and 50 subjects with primary hypertension, in whom angiotensin I-converting enzyme genotype was determined, before and after 15 days of treatment with different antihypertensive drugs. The medication included a calcium channel antagonist, an angiotensin I-converting enzyme inhibitor, and a beta 1-blocker. We also studied the relationship between AT1 receptor gene expression and biochemical parameters of the renin-angiotensin system. AT1 receptor messenger levels were positively correlated with plasma renin activity in both normotensive and untreated hypertensive subjects. Increases of this messenger and plasma angiotensin II levels were correlated with the D allele in the same individuals. AT1 receptor messenger levels decreased significantly with angiotensin I-converting enzyme inhibitor treatment in subjects with the DD genotype, and a significant decrease was observed in subjects with the II and ID genotypes treated with a calcium antagonist. No changes were observed in mRNA with the beta 1-blocker. We conclude that the AT2 receptor is not expressed in peripheral leukocytes and that AT1 receptor messenger levels vary in relation to angiotensin I-converting enzyme genotype and pharmacological treatment. These results suggest that angiotensin I-converting enzyme genotype may be an important factor when deciding on antihypertensive therapy in individuals with primary hypertension.
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PMID:Angiotensin I-converting enzyme genotypes and angiotensin II receptors. Response to therapy. 867 71

Previous studies [Czyzyk-Krzeska et al.: J Neurochem 1992;58:1538] demonstrated the relationship between low O2 breathing and tyrosine hydroxylase (TH) gene expression in chemosensory type I cells of the carotid body. In the present study, we have exposed carotid bodies in vitro to hypoxic superfusion media, and subsequently used the reverse transcriptase-polymerase chain reaction technique to measure relative changes in the TH transcript in an effort to elucidate the cellular mechanisms which regulate TH gene expression. Carotid bodies and superior cervical ganglia (SCG) were exposed for 3 h to superfusion media equilibrated with either 10% O2 or 100% O2 and then rapidly frozen on dry ice prior to extraction of total RNA. Hypoxia elevated TH mRNA in the carotid body 3.63 +/- 0.84-fold (mean +/- SEM), while in contrast, these parameters were unchanged in SCG similarly exposed to hypoxic media. Incubation of carotid bodies in zero Ca2+ superfusates greatly attenuated the increase in TH mRNA evoked by hypoxia (1.39 +/- 0.34-fold increase; p < 0.025 compared to normal Ca2+ group). Likewise, exposure to the guanylate cyclase activator, atriopeptin III (100 nM), attenuated the TH mRNA hypoxic response (p < 0.005), while activation of adenylate cyclase with forskolin (10 microM) tended to elevate the response to low O2. Our data suggest that hypoxia, independent of circulating hormones, induces TH gene expression in the carotid body, and that multiple factors, including [Ca2+] and cyclic nucleotides, may be important components of the signal transduction pathway.
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PMID:Second messenger regulation of tyrosine hydroxylase gene expression in rat carotid body. 870 28

This work extends a recent observation that Otsuka Long-Evans Tokushima Fatty (OLETF) rats show a congenital defect of the cholecystokinin (CCK)-A receptor gene. Expression of CCK-A receptor mRNA in the pancreas, small intestine and brain were not detected in OLETF rats by the reverse transcriptase polymerase chain reaction. In vitro studies showed that the maximal effective concentrations of neuromedin C, acetylcholine and secretin for stimulation of amylase secretion were comparable in both strains, but that CCK-stimulated amylase secretion was observed only in Long-Evans Tokushima Otsuka (LETO) rats. Intracellular cytosolic Ca2+ movement stimulated by acetylcholine and neuromedin C was similar in both strains. In vivo studies showed that the pancreatic secretions in response to secretin and acetylcholine were not impaired in OLETF rats. However, protein responses to neuromedin C and 2-deoxy-D-glucose were impaired in OLETF rats. The findings suggest that pancreatic exocrine functions in OLETF rats are regulated by all neural and peptidergic agents except CCK.
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PMID:Regulation of pancreatic exocrine function in Otsuka Long-Evans Tokushima Fatty (OLETF) rats without gene expression of cholecystokinin-A receptor. 873 76

Stem cell factor, a recently discovered growth factor for hematopoietic stem cells, mast cells, and melanocytes, was initially reported to be produced by fibroblasts. In this study, we investigated the secretion of this factor from human HaCaT cells during in vitro culture and compared it to synthesis by cells in the skin. Release of stem cell factor from freshly cultured keratinocytes was comparable to that of HaCaT cells and was nearly half that produced by fibroblasts and umbilical vein endothelial cells. No stem cell factor was detectable in culture supernatants of melanocytes. HaCaT cells underwent spontaneous differentiation after a period of proliferation until confluency. Depending on duration of culture, they released increasing amounts of stem cell factor (approximately 150 pg/10(6) cells on day 3 (proliferating cells) vs approximately 450 pg/10(6) cells on day 14 (differentiating cells) measured by enzyme-linked immunosorbent assay. Stimulation for 24 h with the calcium ionophore A 23187 (10(-6) to 10(-8) M) further enhanced release. Western blot analysis of HaCaT cell lysates with a stem cell factor antibody revealed two proteins with the known molecular weights of membrane-bound and soluble stem cell factor. By semiquantitative reverse transcriptase polymerase chain reaction, full-length as well as spliced type stem cell factor mRNA was found to be increased in differentiating versus proliferating HaCaT cells. Keratinocytes are thus potentially important sources of stem cell factor in human skin, and HaCaT cells provide a useful model for further studies of stem cell factor from keratinocytes.
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PMID:Release of stem cell factor from a human keratinocyte line, HaCaT, is increased in differentiating versus proliferating cells. 875 66

Calcium-dependent signal transduction is essential to the induction of cytokine expression by stimuli acting through the T cell receptor. In vitro, the immunosuppressant cyclosporine (CyA) blocks this pathway by inhibition of calcineurin (CN) phosphatase activity. But in vivo, patients on CyA have only 50% inhibition of CN and can mount cytokine responses. To simulate this state of partial inhibition, we studied the responses of human peripheral blood mononuclear leucocytes (PBL) in vitro at low CyA concentrations. PBL were challenged in vitro with calcium ionophores or anti-CD3 monoclonal antibody. The induction of IFN-gamma (interferon-gamma) and IL-2 (interleukin 2) steady-state mRNA was studied by Northern blotting and reverse transcriptase-polymerase chain reaction. IFN-gamma was assessed in a radiolabelled antibody binding assay or by ELISA (enzyme-linked immunosorbent assay). CN was assessed by dephosphorylation of a 32P-serine labelled 19 amino acid substrate. CyA inhibited CN with an IC50 (concentration giving 50% inhibition) of 10 ng/ml (95% confidence interval, CI = 8-13 ng/ml). Likewise, the induction of IFN-gamma and IL-2 mRNA by calcium ionophore A23187 was inhibited with IC50 of 14 ng/ml (95% CI = 8-27 ng/ml) and 32 ng/ml (95% CI = 5-178 ng/ml), respectively, while the IC50 for inhibition of IFN-gamma protein secretion was 8 ng/ml (95% CI = 9-18 ng/ml). Partial inhibition of CN also altered the threshold for IFN-gamma induction. CyA 10 ng/ml inhibited IFN-gamma induction by anti-CD3 monoclonal antibody OKT3 significantly more at low OKT3 concentrations (10 ng/ml, mean +/- SEM = 72 +/- 9% inhibition) compared to high OKT3 concentrations (1000 ng/ml, 47 +/- 6%, p < 0.01). Similar results were seen using high and low concentrations of A23187. Finally, cells pretreated with CyA recovered the ability to respond to high concentrations of A23187 (5 microM) faster than low concentrations (0.5 microM). We conclude that the principal defect in lymphocytes with partial CN inhibition is a reduction in maximum cytokine output which is closely related to the degree of CN inhibition. In addition, there is significantly greater inhibition of weak stimuli compared to maximal stimuli. These defects may explain why patients on CyA can have a reduction in immune responsiveness but still retain protection from infection.
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PMID:The functional consequences of partial calcineurin inhibition in human peripheral blood mononuclear leucocytes. 876 5

Skeletal muscle exhibits a wide range in functional phenotype in response to changes in physiological demands. We have observed that, in response to changes in work patterns, alterations in gene expression of some proteins coincide with changes in adenylyl cyclase (AC) activity [Kraus, W.E., J.P. Longabaugh, and S. B. Liggett. Am. J. Physiol 263 (Endocrinol. Metab. 26): E266-E230, 1992]. We now examine AC isoform transcript prevalence in various rabbit skeletal muscles and in response to changing work demands. Using reverse transcriptase-polymerase chain reaction, we detected type II AC isoform transcripts in rabbit skeletal muscle. Ribonuclease protection analyses revealed that expression of the type II isoform significantly correlated with the percentage of fast-twitch type IIb/IId fibers (r2 = 0.765, P < 0.01). When a fast-twitch muscle was converted to a slow-twitch muscle via chronic electrical pacing, expression of type II AC mRNA significantly decreased. This response occurred 3 days after the onset of stimulation (78% decrease) and was still present after 21 days of stimulation (76% decrease). As type II AC is relatively insensitive to calcium regulation while sensitive to protein kinase C (PKC) signaling, these data provide further impetus for investigations of protein kinase A and PKC cross-talk signaling mechanisms in the regulation of gene expression.
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PMID:Regulation of type II adenylyl cyclase mRNA in rabbit skeletal muscle by chronic motor nerve pacing. 877 18

Decreased bone mass has been reported in patients with idiopathic hypercalciuria. Previous studies, using bioassays, have suggested a role of interleukin-1 (IL-1), in the decreased bone mineral density (BMD) of fasting hypercalciuria. The present study was designed to determine which IL-1 fraction (alpha or beta) correlates with bone resorption and whether other known bone resorting cytokines like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) may play a role in this process. Cytokines production was determined by quantitative and specific analysis, enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR). Dual-energy X-ray absorptiometry and cytokine production by unstimulated and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) were determined in a group of 29 patients with recurrent nephrolithiasis (17 hypercalciurics and 12 normocalciurics), and 12 healthy controls. The hypercalciuric subjects showed lower vertebral BMD than the normocalciuric or normal controls. There was no difference in spinal or femoral BMD between absorptive or fasting hypercalciurics. A significant negative correlation existed between urinary calcium excretion and vertebral BMD (r = -0.55, P < 0.01). Basal IL-1 alpha production correlated with vertebral BMD (r = -0.45, P < 0.02). This correlation was not seen with IL-1 beta, IL-6 or TNF-alpha production. LPS-induced IL-6 and TNF-alpha production were enhanced in the hypercalciuric patients, when compared to normocalciurics or controls. Control and normocalciuric subjects showed minimal amounts of IL-1 alpha mRNA. In contrast, hypercalciuric patients showed a significant increase of spontaneous IL-1 alpha mRNA transcription. These results suggest that different cytokines could be involved in the bone resorption process observed in hypercalciuria.
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PMID:Possible role of cytokines on the bone mineral loss in idiopathic hypercalciuria. 877 Sep 75

Here we show that secretory phospholipase A2 (sPLA2) that is immunochemically indistinguishable from type II sPLA2 is (i) stored in neuroendocrine cells, (ii) released in response to neurotransmitters or depolarization, and (iii) involved in the regulation of catecholamine secretion by these cells. Rat brain synaptic vesicle fractions contained PLA2 activity, which was neutralized completely by an antibody raised against rat type II sPLA2. sPLA2 immunoreactive with anti-(type II sPLA2) antibody was released from synaptosomes in response to depolarization evoked by a high concentration of potassium in the presence of Ca2+. Rat pheochromocytoma PC12 cells, which differentiated into adherent cells similar to sympathetic neurons in response to nerve growth factor, were used for the detailed analysis of the dynamics and function of sPLA2 in neuronal cells. Antibody against rat type II sPLA2 precipitated approximately 80% of the PLA2 activity in PC12 cell lysates. Transcript for type II sPLA2 was detected in PC12 cells by reverse transcriptase-PCR. When neuronally differentiated PC12 cells were stimulated with carbamylcholine or potassium, sPLA2 was released into the medium and reached a maximal approximately 40% release by 15 min. Inhibitors specific to type II sPLA2 suppressed catecholamine secretion by PC12 cells which had been activated by carbamylcholine. Furthermore, treatment of PC12 cells with exogenous type II sPLA2 alone elicited catecholamine secretion. These observations indicate that sPLA2 released from neuronal cells may regulate the degranulation process leading to release of neurotransmitters and are compatible with our earlier finding that this enzyme is involved in the degranulation of rat mast cells.
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PMID:Release of secretory phospholipase A2 from rat neuronal cells and its possible function in the regulation of catecholamine secretion. 880 65

1. The Ca2+ permeability of non-NMDA and NMDA receptor channels was studied using a fluorometric flux measurement approach in somata and dendrites of CA1 pyramidal neurones in rat hippocampal slices. For this purpose, the Ca2+ fraction of the total cation current (named 'fractional Ca2+ current') was measured directly from the change in the Ca(2+)-sensitive fura-2 fluorescence at 380 nm excitation wavelength. 2. The fractional Ca2+ current through the somatic NMDA receptor channels was 10.69 +/- 2.13% (mean +/- S.D.) and that through dendritic receptor channels was 10.70 +/- 1.96%. The fractional Ca2+ current was not dependent on the extracellular Mg2+ concentration and its voltage dependence was in agreement with the Goldman-Hodgkin-Katz current equation. 3. AMPA (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate) or kainate applications produced small but significant Ca2+ entry. Fractional Ca2+ currents of 0.58 +/- 0.34% were measured for somatic AMPA applications, 0.68 +/- 0.20% for somatic kainate applications, 0.66 +/- 0.25% for dendritic AMPA applications and 0.61 +/- 0.16% for dendritic kainate applications. 4. The expression pattern of glutamate receptor subunits encoding messenger ribonucleic acids (mRNAs) was analysed with the single-cell reverse transcriptase-polymerase chain reaction (RT-PCR) approach applied to CA1 pyramidal neurones. The AMPA receptor subunits GluR-A, GluR-B and GluR-C, and the NMDA receptor subunits NR2A and NR2B were found to be abundantly expressed in all CA1 pyramidal neurones tested. 5. This study establishes the fractional Ca2+ current through somatic and dendritic NMDA and non-NMDA receptor channels in CA1 pyramidal neurones. The dendritic, presumably synaptic, NMDA receptor channels are highly Ca2+ permeable and have a fractional Ca2+ current closely resembling that of somatic extrasynaptic NMDA receptor channels. Both somatic and dendritic non-NMDA receptor channels are of the 'low Ca2+ permeable' type and have a fractional Ca2+ current that is about twenty times smaller than that of NMDA receptor channels.
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PMID:Fractional Ca2+ currents through somatic and dendritic glutamate receptor channels of rat hippocampal CA1 pyramidal neurones. 881 9

We used differential display of mRNA, a method based on reverse transcriptase-PCR, to identify genes whose expression increases in response to acoustic trauma in the chick basilar papilla. Identifying these genes would provide insight into processes involved in repair of the damaged epithelium or in hair cell regeneration. We compared mRNA from the basilar papilla of normal chicks, from chicks exposed to an octave band noise (center frequency: 1.5 kHz) presented at 118 dB for 6 h, and from chicks exposed to noise and allowed to recover for 2 days. Thus far, we have identified 70 bands that appear to be differentially displayed on DNA sequencing gels; approximately 40 of these bands have been subcloned and sequenced. DNA sequences were compared with sequences in the GenBank database to identify genes with significant (70-85%) sequence identity to known genes. Chick cDNAs identified included: the parathyroid hormone-related protein, an immediate early gene; the delta-subunit of the neuronal-specific Ca2+/calmodulin-regulated protein kinase II; and the GTP-binding protein CDC42, a member of the ras superfamily of G proteins. A fourth cDNA had 84% sequence identity to an uncharacterized human cDNA (expressed sequence tag), indicating that this is a novel gene. Slot-blot hybridization analysis of these cDNAs probed with labeled DNA generated from mRNA from each experimental group indicated higher levels of mRNA for each of these four genes after noise exposure. These results indicate the potential involvement of both Ca2+/calmodulin-mediated signaling and GTPase cascades in the response to noise damage and during hair cell regeneration in the chick basilar papilla.
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PMID:Identification of genes expressed after noise exposure in the chick basilar papilla. 881 3


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