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)

To define the molecular regulation of mast cell phenotype and function optimized procedures must be available to study mRNA from mast cells freshly isolated from tissues. However, rat peritoneal mast cells (PMC) contain large amounts of the proteoglycan heparin, and unfortunately, this molecule which is a potent inhibitor of reverse transcriptase (RT) and Taq polymerase and thus RT-PCR, copurifies with RNA. Here we describe an optimized protocol for extracting and amplifying RNA from rat PMC. Mast cells were isolated from rat peritoneum and a method modified from that of Chomczynski and Sacchi (1987) was used to extract the RNA. Following the removal of heparin by heparinase digestion, first strand cDNA synthesis was primed with oligo-dT and the resulting cDNA was quantified by rapid paper chromatography. The use of a detection system for the reverse transcription reaction ensured that the production of cDNA had occurred and allowed subsequent PCR testing to be optimal. cDNA thus produced can be used to detect relatively specific (histidine decarboxylase) and non-specific (beta-actin) mast cell products. Our PCR studies have shown a 300-fold increase in sensitivity over RNA processed by other methods.
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PMID:Optimization of the isolation and effective use of mRNA from rat mast cells. 905 Sep 42

Histidine decarboxylase (HDC), the only enzyme capable of synthetizing histamine, has been found in many proliferating cells and tissues suggesting a role of histamine in cellular proliferation. In this study expression of HDC and the significance of histamine in the proliferation of peripheral lymphocytes of five healthy persons and six patients with chronic lymphoid leukemia (CLL) was examined. Expression of HDC mRNA and the protein was proved by reverse transcriptase polymerase chain reaction and by immunoblot, respectively. The role of histamine was studied in proliferation assays in the presence of irreversible inhibitor of the HDC (alpha-fluoromethylhistidine--aFMH) and also by competing for the intracellular binding sites of histamine using N,N-diethyl-2, 4-phenylmethyl-phenoxy-ethanamine-HCl (DPPE). By inhibiting the HDC enzyme activity by FMH and blocking the intracellular action of histamine by DPPE, a significant decrease in cell proliferation was observed in mitogen stimulated lymphocytes of healthy donors. In CLL patients the proliferation of leukemic lymphocytes was significantly inhibited by blocking the binding of histamine to intracellular binding sites by DPPE but not by FMH inhibiting only the de novo histamine formation. The observations suggest that HDC has functional relevance in lymphocytes, since mitogen induced lymphocyte proliferation of healthy donors is mainly enhanced by de novo synthesis and subsequent action of intracellular histamine. Alternatively, in constitutively proliferating chronic lymphoid leukemia cells we suggest that the preformed pool but not the de novo synthesized intracellular histamine interferes with cellular proliferation.
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PMID:Histidine decarboxylase in peripheral lymphocytes of healthy individuals and chronic lymphoid leukemia patients. 965 97

Mutants of Pseudomonas fluorescens WCS374 defective in biosynthesis of the fluorescent siderophore pseudobactin still display siderophore activity, indicating the production of a second siderophore. A recombinant cosmid clone (pMB374-07) of a WCS374 gene library harboring loci necessary for the biosynthesis of salicylic acid (SA) and this second siderophore pseudomonine was isolated. The salicylate biosynthesis region of WCS374 was localized in a 5-kb EcoRI fragment of pMB374-07. The SA and pseudomonine biosynthesis region was identified by transfer of cosmid pMB374-07 to a pseudobactin-deficient strain of P. putida. Sequence analysis of the 5-kb subclone revealed the presence of four open reading frames (ORFs). Products of two ORFs (pmsC and pmsB) showed homologies with chorismate-utilizing enzymes; a third ORF (pmsE) encoded a protein with strong similarity with enzymes involved in the biosynthesis of siderophores in other bacterial species. The region also contained a putative histidine decarboxylase gene (pmsA). A putative promoter region and two predicted iron boxes were localized upstream of pmsC. We determined by reverse transcriptase-mediated PCR that the pmsCEAB genes are cotranscribed and that expression is iron regulated. In vivo expression of SA genes was achieved in P. putida and Escherichia coli cells. In E. coli, deletions affecting the first ORF (pmsC) diminished SA production, whereas deletion of pmsB abolished it completely. The pmsB gene induced low levels of SA production in E. coli when expressed under control of the lacZ promoter. Several lines of evidence indicate that SA and pseudomonine biosynthesis are related. Moreover, we isolated a Tn5 mutant (374-05) that is simultaneously impaired in SA and pseudomonine production.
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PMID:Analysis of the pmsCEAB gene cluster involved in biosynthesis of salicylic acid and the siderophore pseudomonine in the biocontrol strain Pseudomonas fluorescens WCS374. 1122 88

We have reported previously that the histamine H(2) receptor (H(2)R) can stimulate the phospholipase C (PLC) signaling pathway in mouse keratinocytes. In the present work, we examined the physiological mechanisms involved in this activation by studying histamine metabolism and H(2)R expression and coupling during mouse keratinocyte differentiation. Ca(2+)-induced differentiation decreased histidine decarboxylase (HDC) mRNA, the enzyme responsible for histamine synthesis, by 68.9+/-5.0%. Concomitantly, intracellular histamine content and its release into the extracellular medium were reduced significantly by 68.2+/-2.0 and 74.1+/-1.7%, respectively. Binding of [3H]tiotidine to H(2)Rs present on the surface of whole cells was also decreased by cellular differentiation [(18.17+/-2.1)x10(4) vs. (6.27+/-0.87)x10(4) sites/cell, undifferentiated and differentiated cells, respectively], without affecting H(2)R affinity. Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of the H(2)R mRNA showed that the expression was also down-regulated at the transcriptional level. Moreover, the inhibition of H(2)R expression strongly affected the ability of the receptor to induce PLC activation. Our findings suggest that H(2)R signaling through the PLC second messenger system is inhibited during keratinocyte differentiation by an autocrine loop involving down-regulation of H(2)R expression and inhibition of histamine metabolism.
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PMID:Regulation of phospholipase C activation by the number of H(2) receptors during Ca(2+)-induced differentiation of mouse keratinocytes. 1203 63

Bone mineral density (BMD) is a major risk factor for osteoporosis. Circulating monocytes may serve as early progenitors of osteoclasts and produce a wide variety of factors important to bone metabolism. However, little is known about the roles of circulating monocytes in relation to the pathophysiology of osteoporosis. Using the Affymetrix HG-U133A GeneChip(R) array, we performed a comparative gene expression study of circulating monocytes in subjects with high and low BMD. We identified in total 66 differentially expressed genes including some novel as well as some already known to be relevant to bone metabolism. Three genes potentially contributing to bone metabolism, CCR3 (chemokine receptor 3), HDC (histidine decarboxylase, i.e. the histamine synthesis enzyme), and GCR (glucocorticoid receptor), were confirmed by quantitative real-time reverse transcriptase-PCR as up-regulated in subjects with lower BMD. In addition, significant negative correlation was observed between expression levels of the genes and BMD Z-scores. These three genes and/or their products mediate monocyte chemotaxis, histamine production, and/or sensitivity to glucocorticoids. Our results suggest a novel pathophysiological mechanism for osteoporosis that is characterized by increased recruitment of circulating monocyte into bone, enhanced monocyte differentiation into osteoclasts, as well as osteoclast stimulation via monocyte functional changes. This is the first in vivo microarray study of osteoporosis in humans. The results may contribute to identification of new genes and their functions for osteoporosis and suggest genetic markers to discern individuals at higher risk to osteoporosis with an aim for preventive intervention and treatment.
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PMID:A novel pathophysiological mechanism for osteoporosis suggested by an in vivo gene expression study of circulating monocytes. 1596 35

Synthesis of histamine in hematopoietic progenitor cells may be one of the earliest events in mastopoiesis. We therefore asked whether the key enzyme involved in histamine production, histidine decarboxylase (HDC), can be used as an immunohistochemical marker for the detection of immature neoplastic mast cells (MC) in patients with MC-proliferative disorders. To address this question, we examined bone marrow biopsy specimens in a cohort of 102 patients with mastocytosis using an antibody against HDC. Independent of the maturation stage of MC, the anti-HDC antibody produced clear diagnostic staining results in all patients with systemic MC disease examined including those with MC leukemia and MC sarcoma, in which MCs are particularly immature. In these patients, expression of HDC was reconfirmed at the messenger RNA level by reverse transcriptase polymerase chain reaction analyses performed with RNA of highly enriched CD117(+) MC. In summary, HDC is expressed in neoplastic MC in patients with systemic mastocytosis independent of the maturation stage of cells or the variant of disease. Histidine decarboxylase should therefore be considered as a new MC marker in the screen panel of antigens used to diagnose high-grade MC malignancies.
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PMID:Immunohistochemical detection of histidine decarboxylase in neoplastic mast cells in patients with systemic mastocytosis. 1656 18

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