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)

The v-type ATPase is a membrane anchored, multi-subunit proton pump, which in freshwater fish appears to play a major role in ionoregulative processes in the apical membrane of specialized gill cells. Very little is known about free-living fish embryos and larvae that are exposed to hypo-osmotic conditions with spawning but do not have their gills fully developed. By using reverse transcriptase-polymerase chain reaction and immunological methods, we could demonstrate the presence of two isoforms of the subunit B of this v-type ATPase in the early development of the zebrafish. Immunohistochemical analysis revealed the presence of one isoform (vatB1) in the apical membrane of embryonic skin cells, while vatB2 has been found ubiquitously. This differential localization of the two isoforms supports the hypothesis that vatB1 is preferentially involved in ionoregulative functions, while vatB2 may be preferentially responsible for acidification of intracellular vesicles.
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PMID:Isoforms vatB1 and vatB2 of the vacuolar type ATPase subunit B are differentially expressed in embryos of the zebrafish (Danio rerio). 1518 41

This paper reviews the contractility and the expression of contractile and regulatory proteins in the detrusor smooth muscle (DSM) following partial bladder outlet obstruction (PBOO) in rabbits. PBOO was surgically induced by partial ligation of the urethra in adult male New Zealand White rabbits. The force generated by DSM strips from normal and obstructed bladders which showed bladder dysfunction, despite detrusor hypertrophy (decompensated bladder, DB) was measured. The expression of contractile and regulatory proteins was analyzed by reverse transcriptase-polymerase chain reaction and Western blotting. The DSM from obstructed DB revealed an overexpression of SM-A myosin heavy chain isoform (associated with decreased maximum velocity of shortening). DSM from sham-operated rabbits showed phasic contractions, whereas the detrusor from DB was tonic, exhibiting slow development of force, a longer duration of force maintenance, and slow relaxation. Rho-kinase inhibitor Y-27632 enhanced the relaxation of precontracted (with 125 mM KCl) DSM strips from DB. The enhancement of relaxation of DB by Y-27632 was associated with dephosphorylation of myosin light chain. The detrusor from normal bladders expresses predominantly the smooth muscle caldesmon (h-CaD), a thin filament-associated protein. However, the DSM from DB shows an overexpression of l-CaD, the non-muscle isoform of CaD. The l-CaD colocalizes with myosin in the cytoplasmic filaments in myocytes. These results show that the alteration of contractility of the detrusor following PBOO is associated with changes in the expression of proteins that form the contractile apparatus and regulate the actomyosin ATPase activity and contraction.
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PMID:Alteration of contractile and regulatory proteins following partial bladder outlet obstruction. 1554 94

Aim of the present work was to investigate the involvement of plasma membrane (PM) H(+)-ATPase (E.C. 3.6.3.6) isoforms of cucumber (Cucumis sativus L.) in the response to Fe deficiency. Two PM H(+)-ATPase cDNAs (CsHA1 and CsHA2) were isolated from cucumber and their expression analysed as a function of Fe nutritional status. Semi-quantitative reverse transcriptase (RT)-PCR and quantitative real-time RT-PCR revealed in Fe-deficient roots an enhanced accumulation of CsHA1 gene transcripts, which were hardly detectable in leaves. Supply of iron to deficient plants caused a decrease in the transcript level of CsHA1. In contrast, CsHA2 transcripts, detected both in roots and leaves, appeared to be unaffected by Fe. This work shows for the first time that a transcriptional regulation of PM H(+)-ATPase involving a specific isoform occurs in the response to Fe deficiency.
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PMID:Two plasma membrane H(+)-ATPase genes are differentially expressed in iron-deficient cucumber plants. 1585 37

The plasma membrane Ca(2+) ATPase (PMCA) is an essential regulator of free intracellular calcium. Recent studies have reported aberrant expression of the PMCA1 gene, a member of the PMCA family, in several cancer cell types. To elucidate the contribution of PMCA1 to oral carcinogenesis, we analyzed genetic and epigenetic changes and mRNA and protein expression in primary oral squamous cell carcinomas (OSCCs), oral premalignant lesions (OPLs), and OSCC-derived cell lines. The PMCA1 gene was epigenetically inactivated, but not mutated in the eight OSCC-derived cell lines tested. In clinical samples, frequent down-regulation of PMCA1 protein expression was found not only in primary OSCCs (43%), but also in OPLs (40%). Real-time quantitative reverse transcriptase-polymerase chain reaction data were consistent with the protein expression status. These results suggest that inactivation of the PMCA1 gene is a frequent and early event during oral carcinogenesis, and gene expression may be regulated by an epigenetic mechanism.
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PMID:Plasma membrane Ca2+ ATPase isoform 1 down-regulated in human oral cancer. 1632 33

Free-living amoebae of the genus Acanthamoeba are causative agents of granulomatous amebic encephalitis and amebic keratitis. Because the virulence of Acanthamoeba culbertsoni cultured in the laboratory is restored by consecutive brain passages, we examined the genes induced in mouse brain-passaged A. culbertsoni by differential display reverse transcriptase polymerase chain reaction (DDRT-PCR). Enhanced A. culbertsoni virulence was observed during the second mouse brain passage, i.e., infected mouse mortality increased from 5% to 70%. Ten cDNAs induced during mouse brain passage were identified by DDRT-PCR and this was confirmed by northern blot analysis. BlastX searches of these cDNAs indicated the upregulations of genes encoding predictive NADH-dehydrogenase, proteasomal ATPase, and GDP-mannose pyrophosphorylase B, which have previously been reported to be associated with A. culbertsoni virulence factors.
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PMID:Identification of differentially expressed cDNAs in Acanthamoeba culbertsoni after mouse brain passage. 1651 77

Telomeres, the protein-DNA complexes at the ends of eukaryotic chromosomes, are essential for chromosome stability, and their maintenance is achieved by the specialized reverse transcriptase activity of telomerase or the homologous recombination pathway in most eukaryotes. Here, we identified a human helicase, hPif1 that inhibits telomerase activity. The primary sequence and biochemical analysis suggest that hPif1 is a potential homologue of Escherichia coli RecD, an ATP-dependent 5' to 3' DNA helicase. Ectopic expression of wild-type, but not the ATPase/helicase-deficient hPif1, causes telomere shortening in HT1080 cells. hPif1 reduces telomerase processivity and unwinds DNA/RNA duplex in vitro. hPif1 preferentially binds telomeric DNA in vitro and in vivo. We propose that the mechanism of hPif1's inhibition on telomerase involves unwinding of the DNA/RNA duplex formed by telomerase RNA and telomeric DNA, and RecD homologues in eukaryotes may have evolved gaining additional functions.
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PMID:The human Pif1 helicase, a potential Escherichia coli RecD homologue, inhibits telomerase activity. 1652 49

The genetically dystonic (dt) rat, an autosomal recessive model of generalized dystonia, harbors an insertional mutation in Atcay. As a result, dt rats are deficient in Atcay transcript and the neuronally-restricted protein caytaxin. Previous electrophysiological and biochemical studies have defined olivocerebellar pathways, particularly the climbing fiber projection to Purkinje cells, as sites of significant functional abnormality in dt rats. In normal rats, Atcay transcript is abundantly expressed in the granular and Purkinje cell layers of cerebellar cortex. To better understand the consequences of caytaxin deficiency in cerebellar cortex, differential gene expression was examined in dt rats and their normal littermates. Data from oligonucleotide microarrays and quantitative real-time reverse transcriptase-PCR (QRT-PCR) identified phosphatidylinositol signaling pathways, calcium homeostasis, and extracellular matrix interactions as domains of cellular dysfunction in dt rats. In dt rats, genes encoding the corticotropin-releasing hormone receptor 1 (CRH-R1, Crhr1) and plasma membrane calcium-dependent ATPase 4 (PMCA4, Atp2b4) showed the greatest up-regulation with QRT-PCR. Immunocytochemical experiments demonstrated that CRH-R1, CRH, and PMCA4 were up-regulated in cerebellar cortex of mutant rats. Along with previous electrophysiological and pharmacological studies, our data indicate that caytaxin plays a critical role in the molecular response of Purkinje cells to climbing fiber input. Caytaxin may also contribute to maturational events in cerebellar cortex.
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PMID:Caytaxin deficiency disrupts signaling pathways in cerebellar cortex. 1709 53

Voltage-gated chloride channels (ClCs) are important mediators of cellular ion homeostasis and volume regulation. In an earlier study, we used immunohistochemical, Western blot, and reverse transcriptase PCR (RT-PCR) approaches to identify ClC-K variants in types II, IV, and V fibrocytes of the rodent spiral ligament. We have now confirmed the expression of ClC-K2 in these cells by in situ hybridization. All three of these fibrocyte subtypes are thought to be involved in cochlear K(+) recycling; thus, it is important to understand the precise mechanisms regulating their membrane conductance and the role played by ClCs in this process. In this study, we report the characterization of a secondary cell line derived from explants from the region of the rat spiral ligament underlying and inferior to the spiral prominence. The cultured cells were immunopositive for vimentin, Na,K/ATPase, Na,K,Cl-cotransporter, carbonic anhydrase isozyme II, and creatine kinase isozyme BB, but not for cytokeratins or Ca/ATPase, an immunostaining profile indicative of the type IV subtype. Evaluation of the cultures by RT-PCR and Western blot analysis confirmed the presence of both ClC-2 and -K2. Whole-cell patch clamp recordings identified two biophysically distinct Cl(-) currents in the cultured cells. One, an inwardly rectifying Cl(-) current activated by hyperpolarization or decreasing extracellular pH corresponded with the properties of ClC-2. The other, a weak outwardly rectifying Cl(-) current regulated by extracellular pH, Cl(-), and Ca(2+) resembled the channel characteristics of ClC-K2 when expressed in Xenopus oocytes. These findings suggest that at least two functionally different chloride channels are involved in regulating membrane anion conductance in cultured type IV spiral ligament fibrocytes.
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PMID:Identification of ClC-2 and CIC-K2 chloride channels in cultured rat type IV spiral ligament fibrocytes. 1733 50

Gastric enterochromaffin-like (ECL) cells release histamine in response to food because of elevation of gastrin and neural release of pituitary adenylate cyclase-activating peptide (PACAP). Acid secretion is at a basal level in the absence of food but is rapidly stimulated with feeding. Rats fasted for 24 h showed a significant decrease of mucosal histamine despite steady-state expression of the histamine-synthesizing enzyme histidine decarboxylase (HDC). Comparative transcriptomal analysis using gene expression oligonucleotide microarrays of 95% pure ECL cells from fed and 24-h fasted rats, thereby eliminating mRNA contamination from other gastric mucosal cell types, identified significantly increased gene expression of the enzymes histidase and urocanase catabolizing the HDC substrate L-histidine but significantly decreased expression of the cellular L-histidine uptake transporter SN2 and of the vesicular monoamine transporter 2 (VMAT-2) responsible for histamine uptake into secretory vesicles. This was confirmed by reverse transcriptase-quantitative polymerase chain reaction of gastric fundic mucosal samples from fed and 24-h fasted rats. The decrease of VMAT-2 gene expression was also shown by a decrease in VMAT-2 protein content in protein extracts from fed and 24-h fasted rats compared with equal amounts of HDC protein and Na-K-ATPase alpha(1)-subunit protein content. These results indicate that rat gastric ECL cells regulate their histamine content during 24-h fasting not by a change in HDC gene or protein expression but by regulation of substrate concentration for HDC and a decreased histamine secretory pool.
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PMID:Fasting-induced changes in ECL cell gene expression. 1753 21

Ty1 reverse transcriptase/RNase H (RT/RH) is exquisitely sensitive to manganese concentrations. Elevated intracellular free Mn(2+) inhibits Ty1 retrotransposition and in vitro Ty1 RT-polymerizing activity. Furthermore, Mn(2+) inhibition is not limited to the Ty1 RT, as this ion similarly inhibits the activities of both avian myeloblastosis virus and human immunodeficiency virus type 1 RTs. To further characterize Mn(2+) inhibition, we generated RT/RH suppressor mutants capable of increased Ty1 transposition in pmr1 Delta cells. PMR1 codes for a P-type ATPase that regulates intracellular calcium and manganese ion homeostasis, and pmr1 mutants accumulate elevated intracellular manganese levels and display 100-fold less transposition than PMR1(+) cells. Mapping of these suppressor mutations revealed, surprisingly, that suppressor point mutations localize not to the RT itself but to the RH domain of the protein. Furthermore, Mn(2+) inhibition of in vitro RT activity is greatly reduced in all the suppressor mutants, whereas RH activity and cleavage specificity remain largely unchanged. These intriguing results reveal that the effect of these suppressor mutations is transmitted to the polymerase domain and suggest biochemical communication between these two domains during reverse transcription.
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PMID:Mn2+ suppressor mutations and biochemical communication between Ty1 reverse transcriptase and RNase H domains. 1753 63


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