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)

Expression of nitric oxide synthase (NOS) was studied in nine human neuroblastoma and two human glioblastoma cell lines. Neuronal NOS (n-NOS) mRNA of approximately 10 kb was detected in four of the nine neuroblastoma cell lines by northern blot analysis using human n-NOS cDNA as a probe. Expression of the n-NOS mRNA was also detected in another neuroblastoma cell line in a subsequent reverse transcriptase polymerase chain reaction (RT-PCR) study, but no n-NOS mRNA expression was observed in the other four neuroblastoma cell lines or in the glioblastoma cell lines. The level of NOS activity correlated well with that of n-NOS mRNA expression in neuroblastoma cell lines expressing n-NOS mRNA. Western blot analysis showed that the n-NOS expressed in neuroblastoma cells was a 160-kDa protein reacted with anti-n-NOS antibody. By using the RT-PCR method, a short n-NOS (n-NOS-2) mRNA with a 315-bp inframe deletion from the entire n-NOS (n-NOS-1) mRNA was detected in the human neuroblastoma cells. The structural diversity of human n-NOS mRNA was demonstrated for the first time.
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PMID:Expression of two types of nitric oxide synthase mRNA in human neuroblastoma cell lines. 751 42

The present study provided evidence for the presence of two forms of nitric oxide synthase(NOS) gene in the human retina. Expression of retinal constitutive type(rbNOS) and inducible type(riNOS) of NOS was detected in human retinal poly A+RNA by reverse transcriptase polymerase chain reaction (RT-PCR) method. The deduced amino acid sequence of the human retinal rbNOS showed more than 99% homology with human brain bNOS and that of riNOS was identical to the chondrocytes inducible iNOS with the exception for one amino acid. These differences in amino acid sequences of rbNOS and riNOS, with their counterparts in human brain and human chondrocytes sequences, were only in the non-cofactor binding sites. Northern blot analysis of the human retinal poly A+RNA and total RNA, using the PCR-amplified riNOS probe revealed the existence of riNOS message with the appearance of the band with the expected size of 4.4kb, while the message for rbNOS was not detectable. This was the first report of the deduced nucleotide sequence identification of two NOS genes from a human tissue, while there had been earlier reports from culture cells.
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PMID:Human retina expresses both constitutive and inducible isoforms of nitric oxide synthase mRNA. 752 17

In the present study we examined the effects of hypobaric hypoxia on neuronal (n) and endothelial (e) nitric oxide synthase (NOS) gene expression in the central and peripheral nervous system. Adult rats were exposed either to normoxia (room air) on to hypobaric hypoxia (0.4 atm) for 4, 12 or 24 h and cerebellum and nodose ganglion representing the central and peripheral neurons, respectively, were removed. Messenger RNAs encoding n- and eNOS as well as beta-actin were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) technique. Hypoxia increased nNOS mRNA expression with maximal changes occurring after 12 h wherein mRNA levels were increased by 10.4 +/- 1.3 and 2 +/- 0.4 fold in nodose ganglion and cerebellum, respectively. Hypoxia, on the other hand, had no significant effect on eNOS and beta-actin mRNA levels. Analysis of nNOS protein and enzyme activity showed near doubling of these variables in both tissues after 24 h of hypoxia, indicating that nNOS protein levels are increased and that the protein is functionally active. These observations demonstrate that 12-24 h of hypobaric hypoxia selectively activates nNOS gene expression, which is reflected in an increase in nNOS protein in central and peripheral neurons. It is suggested that up-regulation of nNOS leads to increased generation of nitric oxide, which in turn may contribute to the readjustments of cardio-respiratory systems during the early stages of chronic hypoxia.
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PMID:Activation of nitric oxide synthase gene expression by hypoxia in central and peripheral neurons. 903 52

Expression and androgen regulation of the gene for neuronal nitric oxide synthase (NOS I) were examined in neurons of the major pelvic ganglia in male rats. Some of these postganglionic neurons innervate the penis and produce nitric oxide, which is believed to play a major role in penile erection. Rats were either castrated or sham operated and implanted with SILASTIC brand capsules filled with powdered testosterone (T) or 5alpha-dihydrotestosterone (5alphaDHT) or left empty. After 4 days, the number of neurons intensely stained for NADPH-diaphorase as well as those giving a NOS I signal in in situ hybridization experiments increased in castrated rats treated with testosterone by 31% and 42%, respectively, relative to those in untreated castrated rats. This suggests that the increase in NADPH-diaphorase activity resulted from enzyme synthesis and was due to a modification of NOS I messenger RNA (mRNA) accumulation. After 7 days, Northern blot analysis showed that castration produced a decrease in the amount of NOS I mRNA relative to that of ribosomal RNA. This decrease was almost prevented by T treatment. No significant differences were observed by reverse transcriptase-PCR between 7-day and 28-day treatments. However, in 7-day castrated rats treated with 5alphaDHT, NOS I signals relative to those of hypoxanthine phosphoribosyltransferase, taken as reference, were significantly higher than those in castrated rats and resembled those in sham-castrated rats, suggesting that 5alphaDHT was probably more potent than testosterone in preventing the decrease in NOS I mRNA levels elicited by castration. These results show that NOS I can be positively regulated by androgens and are consistent with the suggestion that these steroids play a role in the physiological processes of penile erection.
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PMID:Androgens modulate nitric oxide synthase messenger ribonucleic acid expression in neurons of the major pelvic ganglion in the rat. 923 55

The gases nitric oxide (NO) and carbon monoxide (CO) may be involved in hypothalamo-pituitary-adrenal axis (HPA) modulation. In the brain, NO is synthesized by two forms of NO synthase (NOS), a constitutive neuronal form (nNOS) and an inducible form (iNOS). There are also a constitutive heme oxygenase (HO2) and an inducible form (HO1) which generate CO. We have therefore investigated the effect of peripheral lipopolysaccharide (LPS) administration on the gene expression of these enzymes along with interleukin-1beta (IL-1beta) gene expression in the hypothalamus, pituitary and liver. Male Wistar rats (200-250 g body weight) were injected intraperitoneally with endotoxin (Escherichia coli, 055 B5) dissolved in sterile normal saline [250 microg/kg first group, 2.5 mg/kg (second group) and 6.25 mg/kg (third group)] in a final volume of 0.5 ml, or saline alone in the control group. The first and the second groups were studied 1, 3, 8 and 24 h after LPS (n = 4 per group); the third group was studied at 3 h. Total RNA was extracted from the hypothalamus, pituitary and liver, and cDNA was made using standard reverse transcriptase methods. Duplex polymerase chain reaction (PCR) was standardised in order to quantify the expression of a specific gene in relation to the 'house-keeping' gene beta-actin. The specific genes studied were iNOS, nNOS, HO1, HO2 and IL-1beta. The PCR products were separated on agarose gel and densitometric analysis of the bands allowed semi-quantification. In the second group, iNOS and IL-1beta were induced in hypothalamus, pituitary and liver, showing a peak at 3 h (p < 0.001), returning to baseline levels at 24 h. Neuronal NOS was not expressed in the liver under basal conditions or after LPS; in the hypothalamus and pituitary, nNOS was expressed basally but there was no change after LPS. In the first group, iNOS and IL-1beta were again induced in all three tissues studied, but with a delayed time course compared to the second and third groups; the peak change for IL-1beta occurred at 8 h (p < 0.05), again returning to baseline levels at 24 h. The peak for iNOS occurred at 24 h. HO1 and HO2 were expressed in all three tissues under basal conditions; HO1 was increased at 1 h in the liver in the second group, and at 3 h in the pituitary in the third group. There was no change in either HO1 or HO2 in the hypothalamus at any dose at any time point. We conclude that IL-1beta and iNOS are induced in rat hypothalamus and pituitary following various doses of endotoxin. We speculate that while IL-1beta may mediate stimulation of the HPA by endotoxin, NO generation may be involved in the counter-regulation of this response.
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PMID:Endotoxin induces interleukin-1beta and nitric oxide synthase mRNA in rat hypothalamus and pituitary. 950 41

The retinoic acid (RA) and differentiation dependence of constitutive expression of the nitric oxide synthase (NOS) isoforms, iNOS, eNOS, and bNOS, was examined by reverse transcriptase polymerase chain recitation (RT-PCR) in cultured, normal, human, tracheobronchial epithelial (NHTBE) cells. In the presence of RA (RA+), early passage NHTBE cells grown in air-liquid interface (ALI) cultures undergo mucous differentiation; in the absence of RA (RA-), they undergo metaplastic squamous differentiation. Under both conditions the respective differentiated phenotype develops around day 10 of culture. We found that iNOS mRNA levels were much higher in RA+ cultures, expressing the mucous phenotype, than in RA- cultures, expressing the metaplastic squamous phenotype. In contrast, eNOS mRNA levels were much higher in RA- cultures than in RA+ cultures. Expression of bNOS was not significantly affected by the RA status. The pattern of expression of NOS isoforms was then studied during the course of development of the two cellular phenotypes. During the early stages of differentiation, expression of iNOS (RA+) and eNOS (RA-) was very low, indicating that the expression of these two isoforms was not only dependent on the presence or absence of RA, but also on the degree of differentiation. The differentiation dependence of bNOS mRNA was less obvious. Four days of RA treatment of RA- cultures, which reverses the squamous phenotype and restores mucous differentiation, induced iNOS expression in a concentration-dependent manner. eNOS expression was depressed by 10(-8) M RA, while bNOS mRNA levels were slightly reduced by 10(-6) M RA. No NOS proteins were detected in unstimulated RA+ and RA- cultures. iNOS protein was induced by cytokine treatment in RA+ cultures, in contrast to eNOS and bNOS protein levels, which were unaffected. Our studies show that constitutive expression of the NOS isoforms is differentially regulated and that iNOS and eNOS mRNA levels are dependent on the stage of mucous and squamous differentiation, respectively. bNOS expression was only marginally affected by the RA or differentiation status.
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PMID:Expression of nitric oxide synthase isoforms in normal human tracheobronchial epithelial cells in vitro: dependence on retinoic acid and the state of differentiation. 963 56

Nitric oxide synthase (NOS) containing nerve regeneration can be seen six months after unilateral cavernous nerve neurotomy in rats. However, its molecular mechanism is still unknown. It is believed that growth factors are involved in this phenomenon. In this study we investigated the change of NOS containing nerve fibers and the RNA expression of insulin like growth factor (IGF)-I, nerve growth factor (NGF), transforming growth factor (TGF)-alpha, TGF-beta 1, TGF-beta 2. TGF-beta 3 and NOS on the penis after cavernous nerve neurotomy in rats. Male rats were divided into three groups: (1) sham operation (N = 10); (2) unilateral neurotomy of a 5 mm segment of the cavernous nerve (N = 15); and (3) bilateral neurotomy (n = 15). Electrostimulation of the intact cavernous nerve or pelvic ganglion was performed at one, three and six months. Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining was used to identify NOS in the penile nerve fibers. The gene expression for growth factors and bNOS was investigated in corporal tissue by reverse transcriptase-polymerase chain reaction (RT-PCR) using specific oligonucleotide primers. One month after neurotomy, both unilateral and bilateral neurotomy groups showed a significant decrease in NOS-containing nerve fibers on the dorsal and intracavernosal nerves on the side of neurotomy, and a significantly lower mRNA expression of bNOS, IGF-I and TGF-beta 2. At three months, the number of NOS-containing nerve fibers in the unilateral neurotomy group increased only slightly but at six months those in the intracavernosal nerve increased in a significant amount (P < 0.0001), however mRNA expression of bNOS, IGF-I and TGF-beta 2 showed a significant increase as early as at three months. After bilateral neurotomy, the NOS-positive nerve fibers in the dorsal and intracavernosal nerve were significantly decreased at one month and remained so at six months; no erectile response could be elicited by pelvic ganglion stimulation. In the unilateral neurotomy group at six months, more NOS-positive neurons in the pelvic ganglia were found on the intact side than on the side of the neurotomy (P < 0.003), indicating that the regeneration derives from pelvic ganglion neurons on the intact side. Furthermore, electrostimulation in the unilateral neurotomy group revealed a greater maximal intracavernosal pressure and a shorter latency period at six months than at one month (P < 0.014, P < 0.001, respectively). These data suggest that IGF-I and TGF-beta 2 may play a key role in regeneration of NOS-containing nerve fibers in the dorsal and intracavernosal nerves after unilateral cavernous nerve injury.
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PMID:The role of growth factor on regeneration of nitric oxide synthase (NOS)--containing nerves after cavernous neurotomy in the rats. 1046 23

The expression of nitric oxide synthase (NOS) isoforms has been investigated in normal (three subjects) and benign hyperplastic prostate (ten patients) by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). The inducible NOS (iNOS or NOS-2) is not detected in normal prostate, while it is expressed in the prostate of all benign prostatic hyperplasia (BPH) patients, even in the absence of prostatitis or systemic signs of an inflammatory condition. This suggests that sex hormones may be involved in iNOS induction and that there may be a role for NO in the pathogenesis of BPH. Constitutive NOSs (nNOS and eNOS) are expressed in both normal and hyperplastic prostate and are co-expressed in epithelial cells. eNOS, however, is present mainly in the basal layer cells; nNOS seems abundantly expressed in the more superficial cells of the affected prostate. This indicates that the switching between the two constitutive isoforms may be part of the usual process of cell differentiation from the basal to the secretory layer of the epithelium.
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PMID:Nitric oxide synthases in normal and benign hyperplastic human prostate: immunohistochemistry and molecular biology. 1054 79

There is growing evidence that nitric oxide (NO) has an important role in tumor growth. However, information on the expression of NO synthase (NOS) in colorectal cancers is scanty. We therefore investigated the distribution and expression of NOS in human colorectal cancers. The expression of three types of NOS, inducible (iNOS), endothelial (eNOS) and neuronal (nNOS), was examined by immunohistochemistry in 25 cases of colorectal cancer. The expression of iNOS was also investigated at the mRNA level using the reverse transcriptase polymerase chain reaction (RT-PCR) in 6 cases. Correlations were made between iNOS expression and the histopathological findings. Immunoreactive iNOS was detected in the tumor cells in 22 cases (88%) with diffuse cytoplasmic reactions. Expression of iNOS-mRNA detected by RT-PCR in three tumor tissues was over five-fold that in normal mucosa. Intensified immunoreactivity of iNOS was associated with vascular invasion. iNOS expression did not correlate with pathological staging, tumor size, lymph node metastasis, p53 expression or tumor vessel density. Immunoreactive eNOS stained more strongly in the endothelial cells of microvessels within and around the tumor than in the areas remote from the tumor. There is enhanced expression of iNOS and eNOS in human colorectal cancers, which may correlate with tumor growth and vascular invasion.
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PMID:Increased in situ expression of nitric oxide synthase in human colorectal cancer. 1075 99

Much evidence supports a role of nitric oxide (.NO) and peroxynitrite (ONOO(-)) in experimental and idiopathic Parkinson's disease (PD); moreover, an overexpression of neuronal nitric oxide synthase (nNOS) was recently reported in the basal ganglia of PD patients. In accord, we previously found a 50% increased.NO production rate during the respiratory burst of circulating neutrophils (PMN) from PD patients. As PMN express the nNOS isoform, the objective of the present study was to ascertain whether this increased.NO production is representative of nNOS gene upregulation. PMN were isolated from blood samples obtained from seven PD patients and seven age- and sex-matched healthy donors; nNOS mRNA was amplified by reverse transcriptase-polymerase chain reaction and the products were hybridized with a probe for nNOS. Nitrotyrosine-containing proteins and nNOS were detected by Western blot and NO production rate was measured spectrophotometrically by the conversion of oxymyoglobin to metmyoglobin. The results showed that both.NO production and protein tyrosine nitration were significantly increased in PMN isolated from PD patients (PD 0.09 +/- 0.01 vs 0.06 +/- 0.008 nmol min(-1) 10(6) cells(-1); P < 0.05). In addition, five of the seven PD patients showed about 10-fold nNOS mRNA overexpression; while two of the seven PD patients showed an expression level similar to that of the controls; detection of nNOS protein was more evident in the former group. In summary, it is likely that overexpression of nNOS and formation of ONOO(-) in PMN cells from PD patients emphasizes a potential causal role of.NO in the physiopathology of the illness.
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PMID:Overexpression of neutrophil neuronal nitric oxide synthase in Parkinson's disease. 1102 Mar 42


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