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)

This report describes cloning of the bovine alpha 2D-adrenergic receptor (alpha 2D-AR) gene and determination of the transcription start site, unequivocal presence of the alpha 2D-AR transcript in the retina, and pharmacological characteristics of the encoded product. Furthermore, expression of the gene in selected bovine tissues has also been scrutinized. A genomic clone was isolated from lambda EMBL3 library and a 3 kb fragment was subcloned and sequenced. This fragment contained the putative TATA box and the coding region. The encoded receptor was transiently expressed in COS cells. The recombinant receptor expressed pharmacological characteristics almost identical to the wild-type bovine retinal receptor, which were typical of the alpha 2D-AR subtype. RNase protection analysis confirmed the expression of the gene in the retina. The bovine receptor was structurally close to its rat analogue which also encodes the alpha 2D-AR, but, the highest homology was observed with the porcine receptor expressing alpha 2A-AR pharmacological characteristics. Certain structural features of the bovine gene were unique to itself and not shared by any other alpha2-AR subtype. Among the tissues tested using reverse transcriptase-polymerase chain reaction (RT-PCR), the alpha 2D-AR message was the most abundant in retina, followed by the brain and olfactory lobe. Thus, the availability of the bovine receptor gene probe will become an important additional tool in the elucidation of molecular mechanisms behind the alpha 2D-AR physiology in neurosensory processes such as those occurring in the eye and the brain.
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PMID:The bovine alpha 2D-adrenergic receptor gene: structure, expression in retina, and pharmacological characterization of the encoded receptor. 945 Jun 52

Tau protein variants are axonal microtubule-associated phosphoproteins whose expression correlates with developmentally regulated neurite outgrowth. A single gene encodes multiple tau transcripts via complex alternative splicing. We studied the expression of the mRNAs encoding N-terminal variants of tau, and we showed distinct alternative splicing of exons 2 and 3 in nervous tissues of the adult rat, including the inner ear, hippocampus, cortex, striatum, brainstem, cerebellum, olfactory bulb and retina. Using the reverse transcriptase-coupled polymerase chain reaction and in situ hybridization, we then focused our developmental study on hippocampal neurons, both in vivo and in vitro, to address the developmental and spatial expression of the alternatively spliced mRNAs encoding N-terminal variants of tau. Tau mRNAs devoid of exons 2 and 3 were present throughout development, although their levels decreased in adults. Those containing exon 2 but not exon 3 were already present in the hippocampus of newborn rats and their levels increased during the first postnatal week, mainly in the pyramidal cell layer. Tau RNAs containing exons 2 and 3 appeared at the end of this period in the pyramidal cell layer and in the dentate granule cells. Exon 2-containing mRNAs seemed to be associated with cells undergoing axonal sprouting, while exon 3-containing RNAs were expressed in mature neurons that had established their connections. The timing and pattern of tau alternative splicing were maintained in cultured hippocampal neurons, suggesting that splicing processes are independent of the organized connectivity and of the environmental cues provided in vivo. Secondary structure predictions of tau variants revealed that the insertion of the exon 3-encoded domain substantially modifies the secondary structure of the N-terminal region of tau. This N-terminal heterogeneity may confer distinct regulatory roles on the tau variants during ontogeny and may contribute to plasticity in the adult rat brain.
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PMID:Developmentally regulated alternative splicing of mRNAs encoding N-terminal tau variants in the rat hippocampus: structural and functional implications. 951 77

Previously we demonstrated the presence of phenol sulphotransferase (P-ST) in mouse nasal cytosols and identified its zonal location in mouse nasal cavity by staining with an antiserum raised against a rat liver P-ST isoenzyme, PSTg. In the present study a cDNA was isolated from a mouse olfactory cDNA library by immunological screening with the antiserum. The isolated cDNA consisted of 1347 bp with a 912 bp open reading frame encoding a 304-residue polypeptide. Both the nucleotide and deduced amino acid sequences of the cDNA were 94% identical with those of a rat liver P-ST isoenzyme, ST1C1. The expressed enzyme in Escherichia coli displayed high P-ST activity towards phenolic odorants such as eugenol and guaiacol, and it showed a high N-hydroxy-2-acetylaminofluorene sulphation activity in comparison with the rat ST1C1 enzyme. These results indicate that the olfactory P-ST encoded by the cDNA is a mouse orthologue of rat ST1C1; however, expression of the olfactory P-ST mRNA is specific for nasal tissues as revealed by reverse transcriptase-mediated PCR (RT-PCR).
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PMID:Molecular cloning and expression of a cDNA encoding an olfactory-specific mouse phenol sulphotransferase. 956 Mar 27

Neuronal basic helix-loop-helix (bHLH) transcription factors such as neuroD and neurogenin have been shown to play important roles in neuronal development. In the present study, several distinct bHLH DNA fragments were isolated from the zebrafish genomic DNA by a pair of degenerate polymerase chain reaction (PCR) primers deduced from the conserved bHLH domains of neuroD and neurogenins. Based on the bHLH fragments, three complete neuroD-related cDNA clones, including complete coding regions, ndr1a, ndr1b, and ndr2 (ndr for neuroD related), were isolated and assembled by 5' and 3' rapid amplification of cDNA ends (RACE). A phylogenetic analysis indicated the presence of four groups of neuroD-related genes in the neuroD subfamily in vertebrates: neuroD, ndr1a/ndr1b/MATH-2, ndr2/NDRF, and neuroM/MATH3. Expression of the newly isolated neuroD-related genes was examined by reverse transcriptase (RT)-PCR and whole-mount in situ hybridization. Unlike neuroD, which was expressed broadly in primary neurons during early zebrafish development starting from 10 h postfertilization (hpf), expression of ndr1a and ndr1b started relatively late (around 22 hpf) and was restricted to the olfactory system: olfactory bulbs in the telecephalon (ndr1a and ndr1b) and olfactory organs (ndr1b) starting around 22 hpf. Although a faint ndr2 mRNA signal was detected by RT-PCR in early embryos, no ndr2 mRNA was detected by whole-mount in situ hybridization in embryos up to 72 hpf, suggesting that it is expressed rather late. Our observations suggest that the two novel neuroD-related genes, ndr1a and ndr1b, are involved in the development of the olfactory system and perhaps contribute to its functional complexity.
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PMID:A class of neuroD-related basic helix-loop-helix transcription factors expressed in developing central nervous system in zebrafish. 1023 16

Although, since the isolation of pituitary adenylate cyclase-activating polypeptide (PACAP), a wealth of literature has been published describing its localization, binding sites, and biological activities in a variety of mammalian tissues, only very little is known about PACAP in avian species. Therefore, in order to find out the sites of actions of PACAP and to elucidate its physiological significance in birds, we identified a chicken PACAP receptor homologue of the mammalian type I receptors (PAC(1)-Rs). The chicken PACAP type I cDNA sequence was obtained using reverse transcriptase-polymerase chain reaction (RT-PCR) in combination with 3'- and 5'-RACE PCR. This cDNA encodes a 471 amino acid precursor protein, sharing 81-83% sequence identity with mammalian analogs and 76% amino acid identity with the goldfish type I PACAP receptor. Northern blot analysis of chicken brain poly(A)(+)-rich RNA revealed the presence of a 5.5 kb and 7.5 kb PAC(1) receptor transcript. RT-PCR revealed that the chicken PACAP receptor is mainly expressed in the brain and gonads. A smaller amount of the receptor mRNA was found in pituitary, adrenal gland, kidney, intestine, pancreas, lung, and heart tissue. In situ hybridization with specific antisense oligodeoxynucleotide probes showed a widespread distribution of PAC(1) receptor mRNA in the chicken brain, with the highest expression being found in the dorsal telencephalon, olfactory bulb, hypothalamus, optic tectum, and cerebellar cortex. These findings suggest that PACAP affect a variety of functions both in the brain and peripheral tissues of the chicken.
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PMID:Molecular cloning and expression of a chicken pituitary adenylate cyclase-activating polypeptide receptor. 1052 79

Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to examine the effects of acute estrogen and progesterone replacement on relative levels of brain-derived neurotrophic factor (BDNF) mRNA and protein in different regions of the adult rat brain. Adult ovariectomized animals were killed 53 h after receiving estrogen (E53), 53 h after receiving estrogen and 5 h after receiving progesterone (E53P), or 72 h after receiving estrogen and 24 h after receiving progesterone (E72P). Ovariectomized controls were killed 53 and 72 h after receiving vehicle. Tissues from the hippocampus, pyriform cortex, olfactory bulbs, septum, and nucleus basalis/ventral pallidum were dissected. Tissues from the right hemisphere were processed for quantitative RT-PCR analysis of BDNF mRNA, and tissues from the left hemisphere were processed for the detection and quantification of BDNF protein by ELISA. The results demonstrate significant increases in BDNF mRNA in the pyriform cortex of E53- and E53P-treated animals, as well as an increase in BDNF protein in the pyriform cortex of E72P-treated animals, relative to controls. Significant increases in BDNF mRNA were likewise detected in the hippocampus of E53- and E72P-treated animals, but were accompanied by a significant decrease in BDNF protein in the hippocampus of E53P- and E72P-treated animals relative to controls. No significant changes in BDNF mRNA or protein were detected in the olfactory bulbs, frontal cortex, or nucleus basalis/ventral pallidum following hormone treatment; however, an increase in BDNF protein was detected in the septum of E53-treated animals. This may indicate an increase in the retrograde transport of BDNF from the hippocampus to the septum, which could help account for the decrease in BDNF protein detected in the hippocampus following hormone treatment. These findings demonstrate that hormone replacement significantly affects relative levels of BDNF mRNA and protein within specific regions of the brain. These effects may, in turn, contribute to the effects of estrogen replacement on hippocampal connectivity and cognitive processes that have recently been reported.
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PMID:Treatment with estrogen and progesterone affects relative levels of brain-derived neurotrophic factor mRNA and protein in different regions of the adult rat brain. 1053 57

Quantitative reverse transcriptase - polymerase chain reaction was used to analyze the relative expressions of NR1, NR2A, NR2B, NR2C, NR2D, and NR3 subunits of the NMDA receptor in the piriform, entorhinal, visual, and motor cortices as well as in the olfactory bulb of adult rat. The analysis detected clear differences in the relative proportions of the NMDA receptor subunits between the five forebrain regions examined. These differences were particularly striking when the piriform and motor cortices were compared. In the piriform cortex, NR1 was the predominant transcript. The expression of NR2A was only slightly higher than half of that of NR1. NR2B was expressed even at lower levels ( approximately 30% of NR1). NR2C and NR3 were expressed at levels which were approximately 15% of those of NR1. NR2D had the lowest levels of expression ( approximately 3% of NR1). In contrast, NR2B was the predominant transcript in the motor cortical region, where it was expressed at the levels close to 135% of those of NR1 message. NR2A had the levels of expression of approximately 50% of those of NR1. The NR2C expression was close to 25% that of NR1, and the NR2D and NR3 transcripts were totally absent from this cortical area. These findings suggest a significant regional variability of the NMDA receptors in the adult rat forebrain.
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PMID:Expression of NR1, NR2A-D, and NR3 subunits of the NMDA receptor in the cerebral cortex and olfactory bulb of adult rat. 1065 28

Insulin-like growth factors (IGFs) are expressed in defined spatiotemporal patterns during the development of the mammalian central nervous system (CNS). Since IGF expression in avian species is less well documented, we studied here the expression of IGF-I and IGF-II during chicken CNS development, using in situ hybridization and reverse transcriptase-PCR, and compared the results with the expression of the IGF type 1 receptor (IGF-1R). IGF-II expression started early in embryonic life, shortly after the onset of IGF-1R expression. During organogenesis, IGF-II was strongly expressed in kidney, liver and gut primordia, in contrast with IGF-1R mRNA, which is highly enriched in proliferating neuroepithelia. During the second half of embryonic development, IGF-I and IGF-II had distinct expression patterns, suggesting specific roles for each ligand during brain maturation. IGF-II mRNA was found in numerous brainstem nuclei and in the optic tectum, whereas IGF-I mRNA was found predominantly in telencephalic regions. Both ligands were expressed in the cerebellum, but each by different cell layers. Some brain regions (olfactory bulb and olivo-cerebellar system) did not exhibit the postnatal downregulation typical of extrahepatic IGF-I expression, but continued to express IGF-I into adulthood. Purkinje cells expressed IGF-II in the embryo, but switched to IGF-I expression in the adult. The conservation of embryonic and postnatal IGF expression patterns in the CNS between avians and mammals suggests that the involvement of the IGF system in neurogenesis and differentiation, and possibly in neural plasticity and learning, may have arisen early during tetrapode/vertebrate evolution.
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PMID:Expression of insulin-like growth factor-I (IGF-I) and IGF-II in the avian brain: relationship of in situ hybridization patterns with IGF type 1 receptor expression. 1070 8

The sodium channel isoform NaCh6 is abundant in the adult rat brain and is expressed in both neurons and glia (Schaller et al. [1995] J. Neurosci. 15:3231-3242; Krzemien et al. [2000] J. Comp. Neurol. 20:70-83). With reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, and immunolabeling, NaCh6 expression was investigated in the developing rat brain and spinal cord [embryonic day 15 (E15) through postnatal day 28 (P28)]. The relative abundance of the four major central nervous system NaCh subtypes was quantitated with RT-PCR. In all regions that were investigated (olfactory bulb, cortex, hippocampus, cerebellum, and spinal cord), each subtype had a unique pattern of expression. NaCh6 mRNA and protein were not detected in either brain or spinal cord at E15 and E18 by in situ hybridization and immunohistochemistry. Neurons in the hippocampus, cortex, and olfactory bulb began to express NaCh6 mRNA and protein shortly after birth. The mRNA signal peaked at P7-P14, and protein expression increased as development proceeded. NaCh6 mRNA was detected at P1 in the cerebellum, and a nonuniform distribution of NaCh6 immunoreactivity in both Purkinje cells and granule cells was observed by P7-P14. NaCh6 protein was expressed in granule cells as soon as they left the proliferative phase and began to migrate. Both NaCh6 mRNA and protein were detected in the spinal cord at P1 and were expressed clearly at P7 in motor neurons. The time course of appearance of NaCh6 in postnatal development is consistent with the development of neurologic symptoms in med and jolting mice, which have mutations in the mouse ortholog of NaCh6.
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PMID:Developmental and regional expression of sodium channel isoform NaCh6 in the rat central nervous system. 1074 21

Calcium agonists induce membrane depolarization in endothelial cells through an unknown mechanism. Present studies tested the hypothesis that pulmonary artery endothelial cells express a cyclic nucleotide-gated (CNG) cation channel activated by store-operated calcium entry to produce membrane depolarization. In the whole-cell configuration, voltage-clamped cells revealed a large non-inactivating, outwardly rectifying cationic current in the absence of extra- or intracellular Ca(2+) that was reduced upon replenishment of Ca(2+). The inward current was non-selective for K(+), Na(+), Cs(+), and Rb(+) and was not inhibited by high tetraethylammonium concentrations. cAMP and cGMP stimulated the current and changed the cation permeability to favor Na(+). Moreover, 8-bromo-cAMP stimulated the current in voltage-clamped cells in the perforated patch mode. The cationic current was inhibited by the CNG channel blocker LY83,583, and reverse transcriptase-polymerase chain reaction cloning identified expression of a CNG channel resembling that seen in olfactory neurons. Activation of store-operated calcium entry using thapsigargin increased a current through the CNG channel. Stimulation of the current paralleled pulmonary artery endothelial cell membrane depolarization, and both the current and membrane depolarization were abolished using LY83,583. Taken together, these data demonstrate activation of store-operated calcium entry stimulates a CNG channel producing membrane depolarization. Such membrane depolarization may contribute to slow feedback inhibition of store-operated calcium entry.
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PMID:Cyclic nucleotide-gated channels mediate membrane depolarization following activation of store-operated calcium entry in endothelial cells. 1076 97


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