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 granule proteins are among the most abundant and characteristic proteins of myeloid cells. They are essential for the antimicrobial activity of these cells and they provide important markers for the differentiation stage of the myeloid series and for the diagnosis of myeloid leukemias. In acute promyelocytic leukemia (APL) there is high production of myeloperoxidase, and its cytochemical detection as well as the t(15;17) chromosomal translocation are important markers in the diagnosis of this acute myelogenous disease. The expression of other granule protein genes in APL has not been systematically determined. We have used the reverse transcriptase-polymerase chain reaction (RT-PCR) method to determine the pattern of expression of granule protein genes at the mRNA level in APL cells. We have examined the expression of the primary granule proteins defensin, myeloperoxidase, elastase, and cathepsin G; the secondary granule proteins lactoferrin, collagenase, and transcobalamin; as well as lysozyme, a protein reportedly found in both primary and secondary granules. mRNAs for all of these granule proteins were present in normal bone marrow mononuclear cells. We found that APL cells from three patients contain, in addition to myeloperoxidase mRNA, mRNAs for elastase, cathepsin G, and lysozyme. One patient had faint but detectable lactoferrin mRNA signal, but collagenase and transcobalamin mRNAs were not detectable in this patient. Defensin mRNA was found in one of the three APL patients, and all the primary granule protein mRNAs measured were found to be expressed in the APL cell line NB4. None of the secondary granule protein mRNAs measured were detectable in NB4 cells. After treatment with retinoic acid (RA), which induces neutrophil maturation of these cells, weak induction of lactoferrin and collagenase but not transcobalamin was observed. However, in view of the weak transcobalamin signal observed in normal bone marrow, the absence of transcobalamin in RA-induced NB4 cells must be interpreted with caution. Interestingly, elastase and cathepsin G mRNA disappeared after RA induction, whereas defensin and myeloperoxidase mRNAs remained present. These findings indicate that granule protein mRNAs are regulated separately and differently, and that only minimal expression of secondary granule protein genes can occur in APL cells.
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PMID:Expression of granule protein mRNAs in acute promyelocytic leukemia. 811 51

Paneth cells, secretory epithelial cells of the small intestinal crypts, are proposed to contribute to local host defense. Both mouse and human Paneth cells express a collection of antimicrobial proteins, including members of a family of antimicrobial peptides named defensins. In this study, data from an anchored polymerase chain reaction (PCR) strategy suggest that only two defensin mRNA isoforms are expressed in the human small intestine, far fewer than the number expressed in the mouse. The two isoforms detected by this PCR approach were human defensin family members, HD-5 and HD-6. The gene encoding HD-6 was cloned and characterized. HD-6 has a genomic organization similar to HD-5, and the two genes have a striking pattern of sequence similarity localized chiefly in their proximal 5'-flanking regions. Analysis of human fetal RNA by reverse transcriptase-PCR detected enteric defensin HD-5 mRNA at 13.5 weeks of gestation in the small intestine and the colon, but by 17 weeks HD-5 was restricted to the small intestine. HD-6 mRNA was detectable at 13.5-17 weeks of gestation in the small intestine but not in the colon. This pattern of expression coincides with the previously described appearance of Paneth cells as determined by ultrastructural approaches. Northern analysis of total RNA from small intestine revealed quantifiable enteric defensin mRNA in five samples from 19 24 weeks of gestation at levels approximately 40-250-fold less than those observed in the adult, with HD-5 mRNA levels greater than those of HD-6 in all samples. In situ hybridization analysis localized expression of enteric defensin mRNA to Paneth cells at 24 weeks of gestation, as is seen in the newborn term infant and the adult. Consistent with earlier morphological studies, the ratio of Paneth cell number per crypt was reduced in samples at 24 weeks of gestation compared with the adult, and this lower cell number partially accounts for the lower defensin mRNA levels as determined by Northern analysis. Low levels of enteric defensin expression in the fetus may be characteristic of an immaturity of local defense, which is thought to predispose infants born prematurely to infection from intestinal microorganisms.
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PMID:Human enteric defensins. Gene structure and developmental expression. 862 37

Cryptdins are antimicrobial peptides of the defensin family that are expressed specifically by Paneth cells in small intestinal crypts (M.E. Selsted, S.I. Miller, A.H. Henschen, and A.J. Ouellette. J. Cell Biol. 118: 929-936, 1992), and at least 17 cryptdin isoforms have been reported in mouse small intestine (A.J. Ouellette, M.M. Hsieh, M.T. Nosek, D.F. Cano-Gauci, K.M. Huttner, R.N. Buick, and M.E. Selsted. Infect. Immun. 62: 5040-5047, 1994). Analysis of cryptdin gene expression in adult mouse small bowel revealed that the cryptdin-4 isoform is differentially expressed along the proximal-to-distal intestinal axis. By peptide-specific reverse transcriptase-polymerase chain reaction-based assays, cryptdin-4 mRNA was found to be absent from the proximal small bowel, increasing to maximal levels in the ileum. In contrast, intestinal content of cryptdin-1 and -5 mRNAs was equivalent in duodenum, jejunum, and ileum, and Northern blot hybridization experiments were consistent with both sets of data. Similarly, individual crypts isolated from duodenum contain cryptdin-1 mRNA but not cryptdin-4 mRNA. Taken together, the results show that Paneth cells are heterogeneous, depending on their position along the longitudinal axis of the small bowel. The positional specificity of defensin gene expression suggests that cryptdins may be useful markers for investigating the establishment and maintenance of this epithelial lineage in the mouse small intestine.
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PMID:Positional specificity of defensin gene expression reveals Paneth cell heterogeneity in mouse small intestine. 876 Jan 9

We have isolated a 454-bp cDNA that encodes a novel fruit specific defensin from bell pepper (Capsicum annuum). The encoded 75-amino-acid polypeptide contains an N-terminal domain characteristic of a signal peptide and a 48-amino-acid mature domain named J1. The mature protein, from which the N-terminal amino acid sequence was determined, contains eight cysteines that from four intramolecular disulfide bridges, suggesting a monomeric form for J1. In healthy fruits J1 is undetectable at the green stage but high levels accumulate during ripening. In wound areas of the green fruit the accumulation of J1 dramatically increased, suggesting a role for J1 in the plant's defense response. Moreover, we have demonstrated that J1 possesses an antifungal activity. We have isolated and characterized the corresponding two homologous genes (j1-1 and j1-2) that exist in the bell pepper genome. Both genes are interrupted by the insertion, at the same position, of one intron of 853 bp for j1-1 and 4900 bp for j1-2. Northern blot and reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism analyses revealed that j1-1 transcripts are present only in fruits, only in trace amounts in mature green fruits, and that they accumulate to high levels in fully ripe fruits, whereas no j1-2 transcripts were detected in the samples monitored.
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PMID:Fruit-specific expression of a defensin-type gene family in bell pepper. Upregulation during ripening and upon wounding. 888 77

In rodents, the four intestinal epithelial cell lineages differentiate and become morphologically distinct during the first 2-3 postnatal wk. In studies reported here, reverse transcriptase-polymerase chain reaction (RT-PCR)-based assays detected Paneth cell defensin mRNAs in intestinal RNA from 1-day-old (P1) mice before crypt formation and maturation of the epithelium. Analysis of these defensin-coding RT-PCR products from P1 mice showed that 69% of clones sequenced coded for cryptdin-6, suggesting that it is the most abundant enteric defensin mRNA in the newborn. Paneth cell mRNAs, including cryptdins-4 and -5, lysozyme, matrilysin, and defensin-related sequences, also were detected in RNA from P1 mouse intestine. Unlike adult mice, where only Paneth cells are immunopositive for cryptdin, cryptdin-containing cells were distributed throughout the newborn intestinal epithelium and not in association with rudimentary crypts. Cryptdin immunoreactivity in the P1 mouse intestine was specific for intracellular granule contents, and immunofluorescent detection of cryptdins on mucosal surfaces suggested that the peptides are released into the intestinal lumen in P1 mice Defensin secretion may contribute to innate immunity of the neonatal intestine before the presence of distinguishable Paneth cells.
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PMID:Cryptdin gene expression in developing mouse small intestine. 903 94

During the development of Plasmodium sp. within the mosquito midgut, the parasite undergoes a series of developmental changes. The elongated ookinete migrates through the layers of the midgut where it forms the oocyst under the basal lamina. We demonstrate here that if Aedes aegypti or Anopheles gambiae, normally susceptible to Plasmodium gallinaceum and P. berghei, respectively, are immune activated by the injection of bacteria into the hemocoel, and subsequently are fed on an infectious bloodmeal, there is a significant reduction in the prevalence and mean intensity of infection of oocysts on the midgut. Only those mosquitoes immune activated prior to, or immediately after, parasite ingestion exhibit this reduction in parasite development. Mosquitoes immune activated 2-5 days after bloodfeeding show no differences in parasite burdens compared with naive controls. Northern analyses reveal that transcriptional activity for mosquito defensins is not detected in the whole bodies of Ae. aegypti from 4 h to 10 days after ingesting P. gallinaceum, suggesting that parasite ingestion, passage from the food bolus through the midgut, oocyst formation, and subsequent release of sporozoites into the hemolymph do not induce the production of defensin. However, reverse transcriptase-PCR of RNA isolated solely from the midguts of Ae. aegypti indicates that transcription of mosquito defensins occurs in the midguts of naive mosquitoes and those ingesting an infectious or noninfectious bloodmeal. Bacteria-challenged Ae. aegypti showed high levels of mature defensin in the hemolymph that correlate with a lower prevalence and mean intensity of infection with oocysts. Because few oocysts were found on the midgut of immune-activated mosquitoes, the data suggest that some factor, induced by bacterial challenge, kills the parasite at a preoocyst stage.
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PMID:Mosquito-Plasmodium interactions in response to immune activation of the vector. 992 43

Defensins are widely distributed and broad-spectrum antimicrobial peptides with activities against bacteria, fungi, and enveloped viruses. Defensins have been isolated from granules of neutrophils from humans, rabbits, rats, and guinea pigs. They have also been found in lung macrophages as well as in Paneth cells of the human, rabbit, and mouse small intestine. The human beta-defensin-2 was recently isolated from human skin. In this study, we detected the expression of mRNA for the defensin cryptdin in BALB/c mouse skin by means of reverse transcriptase PCR amplification. Expression was also detected in dispase-separated epidermis and cultured keratinocytes, but expression was not detected in fibroblasts. The expression of cryptdin mRNA was found to begin on embryonic day 17.5. As determined with specific primers, the cDNA sequence cloned from the skin was found to be identical to that previously reported for cryptdin-5. cDNA derived from cultured keratinocytes demonstrated the sequences of the cryptdin-6 and cryptdin-1 isoforms. In situ hybridization analysis showed that the mRNA of cryptdin was expressed in the suprabasal keratinocytes of the skin in embryonic and neonatal days and then shifted to the hair bulbs in the skin of adult mice.
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PMID:Detection of cryptdin in mouse skin. 1022 32

Multicellular organisms utilize a battery of extracellular and cellular mechanisms to defend against microbial infiltration. Among the armamentarium used by the small intestine to defend against microbial invasion are antimicrobial peptides called defensins. We previously have shown that gut barrier function is impaired following hemorrhagic shock, resulting in translocation of bacteria or endotoxin. Using a rat model, we examined the effect of hemorrhagic shock on alpha-defensin expression. We utilized the anchored reverse transcriptase PCR strategy to isolate a rat enteric defensin cDNA. The cDNA is 406 bases in length and encodes a putative prepro-enteric defensin that we have named rat defensin 5 (RD-5). RD-5 expression is restricted to the small intestine and is specifically localized by in situ hybridization to the Paneth cells. A 10-fold increase in its steady state levels was observed in the distal intestine immediately after the termination of shock. This is the first study to show that enteric defensins are inducible following injury. We suggest that enteric defensins may contribute to the complex and integrated barrier function of the intestinal mucosal surface.
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PMID:Induction of a rat enteric defensin gene by hemorrhagic shock. 1045 32

One component of host defense at mucosal surfaces appears to be epithelium-derived antimicrobial peptides. Molecules of the defensin and cathelicidin families have been studied in several species, including human and mouse. We describe in this report the identification and characterization of rhesus monkey homologues of human mucosal antimicrobial peptides. Using reverse transcriptase PCR methodology, we cloned the cDNAs of rhesus monkey beta-defensin 1 and 2 (rhBD-1 and rhBD-2) and rhesus monkey LL-37/CAP-18 (rhLL-37/rhCAP-18). The predicted amino acid sequences showed a high degree of homology to the human molecules. The expression of the monkey antimicrobial peptides was analyzed using immunohistochemistry with three polyclonal antibodies to the human molecules. As in humans, rhesus monkey antimicrobial peptides are expressed in epithelia of various organs. The present study demonstrates that beta-defensins and cathelicidins of rhesus monkeys are close homologues to the human molecules and indicate that nonhuman primates represent valid model organisms to study innate immune functions.
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PMID:Rhesus monkey (Macaca mulatta) mucosal antimicrobial peptides are close homologues of human molecules. 1187 4

From the seeds of the Yunnan bean, we purified an antifungal peptide using affinity chromatography on Affi-gel blue gel, FPLC-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 75. The antifungal peptide was adsorbed on Affi-gel blue gel at pH 7.8 and Mono S at pH 4.5. It exhibited a molecular mass of 6.5 kDa in both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its N-terminal sequence closely resembled defensin-related peptides. The peptide exerted antifungal activity toward the fungal species Fusarium oxysporum and Mycosphaerella arachidicola, with an IC50 of 2 microM for the former fungus and 10 microM for the latter. It manifested a weaker mitogenic activity toward murine splenocytes than Concanavalin A. It also displayed antiproliferative activity on a murine leukemia (L1210), a hepatoma (HepG2), and a murine leukemia (M1) cell line. It inhibited human immunodeficiency virus-1 reverse transcriptase with an IC50 of 200 microM.
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PMID:Gymnin, a potent defensin-like antifungal peptide from the Yunnan bean (Gymnocladus chinensis Baill). 1449 73


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