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

---

Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly ADP-ribosylation of two mouse lymphoma cell lines, L5178Y (LS) and the radiation and alkylating agent resistant derivative AII, was investigated by uptake of [3H]NAD by permeabilised cells into acid-precipitable material that was sensitive to phosphodiesterase but insensitive to DNase and RNase. Basal activities in both lymphoma lines were 3-4-fold greater than in mouse L1210 leukaemia cells. However, total endogenous poly (ADP-R) polymerase activity in both L5178Y cell lines, stimulated by a large excess of DNase in the presence of Triton X-100, was less than half the activity in L1210 cells. Doses of N-methyl-N-nitrosourea (MNU) that produced 20-50% survival of colony-forming units increased poly (ADP-R) in both lymphoma lines by only 25% compared with 377% in L1210 cells when synthesis was measured immediately after a 30-min exposure of MNU. During the first 24 h after MNU AII cells produced a peak of activity that was not seen with LS cells. A second peak was seen in both cell lines between 24 and 48 h following MNU. Concentrations of 3-aminobenzamide (3AB) above 2.5 mM inhibited colony-forming ability of lymphoma cells and equally inhibited uptake of [14C]formate into protein, RNA and DNA indicating that 3AB behaves as a general metabolic poison. Concentrations of 3AB in the toxic range of 3-10 mM inhibited poly (ADP-R) synthesis but no degradation of the polymer was observed. Non-toxic concentrations of 3AB potentiated cell killing by MNU to a similar degree in both lymphoma cell lines. In conclusion, we have found little evidence to support the hypothesis that the differential sensitivity of LS and AII is related to poly ADP-ribosylation. Compared with other mouse cells, L5178Y cells appear deficient in poly (ADP-R) polymerase and poly (ADP-R) glycohydrolase activities.
Carcinogenesis 1985 Jul
PMID:Poly (ADP-ribose) metabolism in alkylated mouse L5178Y cells. 299 Jul 53

Histological studies using paired immunofluorescence staining and peroxidase-anti-peroxidase staining were performed on sections of rat livers with an antiserum specific for the 2-acetylaminofluorene (AAF)-DNA adduct N-deoxyguanosin-(8-yl)-aminofluorene (dG-8-AF). This is the predominant adduct in rat liver DNA at 5 (80%) and 28 (100%) days of AAF feeding. Nuclear staining was observed in livers of male Fischer rats fed 0.02% AAF for these time periods, and was not present in livers of animals fed control diet or detected when specific antiserum, first absorbed with the immunogen adduct, was utilized. In addition, nuclear staining was unchanged after incubation with RNase and abolished after incubation with DNase. Adducts were not readily detectable when whole-liver adduct concentrations were less than an average of 10(5) adducts per cell (30-50 fmol/micrograms DNA). The overall pattern of adduct distribution in livers of AAF-fed animals was distinctly non-uniform. A predominance of nuclear staining was found in the periportal areas by both immunofluorescence and immunoperoxidase procedures. In contrast, staining was very weak in the centrilobular areas. When animals were fed AAF for 28 days and control diet subsequently for 7, 14, 21 or 28 days, the overall intensity of the immunohistochemical staining decreased with time on control diet. However, the pattern of localization remained the same as in livers of rats fed AAF for 28 days, with the predominance of adducts being in the periportal areas. In male rats fed 0.02% AAF for 8 weeks, foci positive for gamma-glutamyltranspeptidase (GGT) became apparent, and the nuclei in these areas showed no immunofluorescence, indicating the absence of detectable levels of the dG-8-AF adduct. Twenty adduct-negative areas in the median lobes of three rat livers were positive for GGT, which suggests that loss of ability to form adducts in these regions occurs concomitantly with early phenotypic changes.
Carcinogenesis 1986 Jan
PMID:Immunohistochemical localization of DNA adducts in rat liver tissue and phenotypically altered foci during oral administration of 2-acetylaminofluorene. 351 Jul 47

A murine monoclonal IgG2b with high affinity and specificity for O6-methylguanine was developed. This allowed visualization of this adduct in paraffin-embedded sections by indirect fluorescence or immunoperoxidase methods. The antibody was used to study and compare the formation and persistence of this adduct detected by immunohistochemistry and the presence of 14C methyl by autoradiography in sections from adult human pancreas explants exposed to [14C methyl]dimethylnitrosamine (DMN) and organ-cultured for up to 7 days. O6-methylguanine was detectable randomly and with varied intensity in parenchymal cell nuclei and cytoplasms, 6 h after exposure to DMN. Following RNase treatment, however, only 7.5% of nuclei revealed measurable staining. The positive nuclei decreased to 2.5% within 24 h and remained about the same throughout the 7 days of culture. This correlated well with the change in percentage of positive nuclei for 14C methyl autoradiographic grains which were selectively condensed over the O6-methylguanine-stained nuclei. The data demonstrate a subpopulation of repair-deficient parenchymal cells of human pancreas exposed to DMN.
Carcinogenesis 1987 Jun
PMID:Visualization of O6-methylguanine in target cell nuclei of dimethylnitrosamine-treated human pancreas by a murine monoclonal antibody. 360 82

The localization of benzo[a]pyrene-deoxyguanosine adducts was studied by indirect immunofluorescence in cultured BALB/c epidermal cells exposed to (+/-) 7 alpha, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (the anti-isomer) utilizing an antiserum specific for the major benzo[a]pyrene-deoxyguanosine adduct in DNA. This antiserum does not cross-react with benzo[a]pyrene or DNA alone. When cultured keratinocytes were incubated with the carcinogen for 1 h, the immunofluorescence was localized in the nucleus as intense spots on a background of diffuse fluorescence. Fluorescence was absent from cells not exposed to carcinogen and from carcinogen-exposed cells incubated with normal rabbit serum in place of the antiserum. Fluorescence was abolished when the specific antiserum was absorbed with the immunogen DNA prior to incubation with cells, and substantially diminished when exposed cells were preincubated with deoxyribonuclease before the application of the specific antiserum. Incubation of exposed cells with ribonuclease prior to incubation with the specific antiserum removed the bright fluorescent spots and resulted in fluorescent nuclei containing dark sports in similar frequency. Dose-response studies in which benzo[a]pyrene-deoxyguanosine adducts were quantified by enzyme-linked immunosorbent assay and compared with intensity of immunofluorescence demonstrated that decreasing doses of the carcinogen resulted in fewer numbers of adducts as well as proportionally less fluorescence. When cells were exposed to non-toxic doses of the activated carcinogen for 1 h, nuclear fluorescence was detectable in immediately-fixed cells but faded to non-detectable levels when cells were washed and cultured for an additional 24-48 h before fixation.
Carcinogenesis 1982
PMID:Indirect immunofluorescent localization of benzo[a]pyrene adducted to nucleic acids in cultured mouse keratinocyte nuclei. 628 90

The majority of carcinomas of the pancreas in humans are of ductal origin and are located in the head of the gland. These clinical characteristics however, are not affected in traditional animal models of the disease. Partial pancreatic duct obstruction with ductal epithelial hyperplasia was produced in the Syrian golden hamster by wrapping the head of the pancreas with cellophane tape. Wrapped and unwrapped animals were then exposed to an exogenous carcinogen (N-nitrosobis[2-oxopropyl]amine). Assay of serum ribonuclease activity was used as a marker of disease. Invasive lesions developed in both groups of animals. Fifty percent of the tumors in the Group II (cellophane wrap and N-nitrosobis [2-oxopropyl] amine) hamsters were located in the head of the gland and were of ductal origin. All tumors in animals receiving N-nitrosobis [2-oxopropyl]amine alone (Group I) occurred peripherally and were derived from ductular or acinar tissue. Elevation of serum ribonuclease activity was noted early in the course of carcinogenesis, thereafter returning to normal, which may explain the clinical controversy regarding this marker. This new model should enhance our knowledge of the interrelationships between etiologic factors, precursor lesions, and pancreatic cancer.
...
PMID:Development of experimental cancer in the head of the pancreas by surgical induction of tissue injury. 669 41

We reported (Scates et al. Carcinogenesis 1994, 15, 2945-2948) that incubating a range of bile acids with DNA in vitro, with or without exogenous metabolic activation, gave no evidence of DNA adduct formation as judged by the nuclease P1 method of 32P-postlabelling. In contrast Hamada et al. (Carcinogenesis 1994, 15, 1911-1915), also using postlabelling, claimed that chenodeoxycholic acid, lithocholic acid, glycolithocholic acid and taurolithocholic acid bound covalently to DNA in vitro. To investigate this discordance we incubated solutions of salmon sperm DNA for 1 h at 37 degrees C with 1 mg/ml of cholic acid, chenodeoxycholic acid, lithocholic acid, glycolithocholic acid or taurolithocholic acid. Each incubate was extracted extensively with diethyl ether after which a sample of DNA was taken and 32P-postlabelled using the nuclease P1 method. The DNA in the remaining incubate was precipitated from high salt solution with ethanol. Aliquots of this DNA were postlabelled. The remainder of the DNA was purified with proteinase-K, ribonuclease, phenol-chloroform, precipitated and postlabelled. Parallel incubates were made with the same bile acids, under the same conditions but in the absence of DNA and were then extracted, precipitated and postlabelled as described above. When DNA was present in the incubate but was not precipitated, chenodeoxycholic acid, lithocholic acid, glycolithocholic acid and taurolithocholic acid, but not cholic acid, produced spots similar to those reported by Hamada et al. No such spots were seen when DNA was postlabelled after precipitation, or after precipitation and purification. These same bile acids produced spots when postlabelled in the absence of DNA, but spots were absent when these incubates were precipitated and purified before postlabelling. We conclude that the spots obtained when bile acids are incubated with DNA which is not precipitated from high salt before it is postlabelled are technical artefacts, and cannot be regarded as evidence that bile acids bind covalently to DNA to form adducts. We also confirm reports (Vulimiri et al. Carcinogenesis 1994, 15, 2061-2064) that bile acids alone can produce spots when incubated with T4 polynucleotide kinase and [gamma-32P]ATP.
Carcinogenesis 1995 Jul
PMID:Appearance of artefacts when using 32P-postlabelling to investigate DNA adduct formation by bile acids in vitro: lack of evidence for covalent binding. 761 81

In chickens, as in all vertebrates, tissue-specific expression of aldolase isozymes A, B, and C is developmentally coordinated. These developmental transitions in aldolase expression have been studied most extensively by charting enzyme activity during normal and abnormal development of specific vertebrate tissues. Indeed, aldolase expression has been a key marker for normal differentiation and for retrodifferentiation during carcinogenesis. Aldolase expression during chicken myoblast differentiation offers a model for investigating the regulatory mechanisms of these developmental transitions at the level of gene expression. For these studies, cDNAs encoding the most isozyme-specific regions of both chicken aldolase A and C were cloned. The chicken aldolase A cDNA represents the first report of this sequence. Aldolase steady-state mRNA expression was measured during chicken myoblast differentiation in primary cultures using RNase protection assays with cRNA probes generated from these aldolase cDNA clones. Steady-state mRNA for aldolase C, the predominant embryonic aldolase isozyme in chickens, did not significantly change throughout myoblast differentiation. In contrast, expression of steady-state mRNA for aldolase A, the only aldolase isozyme found in adult-skeletal muscle, was not detected until after myoblast fusion was approximately 50% completed. Aldolase A expression gradually increased throughout myoblast differentiation until approximately 48 h after fusion was completed when there was a dramatic increase. These results are contrasted with those of Turner et al. (1974) [Dev Biol 37:63-89] that showed a coordinated switch in isozyme activities between the embryonic aldolase C and the muscle-specific aldolase A. This discordant expression indicates that the aldolase A and C genes may employ different regulatory mechanisms during myoblast differentiation.
...
PMID:Noncoordinate changes in the steady-state mRNA expressed from aldolase A and aldolase C genes during differentiation of chicken myoblasts. 776 78

Pancreatic ductal adenocarcinomas induced in the Syrian golden hamster (SGH) by N-nitrosobis(2-oxopropyl)amine share many similarities with the human disease, including mutations of the K-ras oncogene. In vitro carcinogenesis studies with immortal SGH pancreatic duct cells indicate that neoplastic transformation in this system can occur without mutational inactivation of p53 suppressor gene. In this study we extend the genetic analysis of the in vivo SGH model to increase the number of cases analyzed for the status of K-ras and to determine further the spectrum of alterations involved; we have studied the status of the p53, DCC, and Rb-1 suppressor genes and the status of the mdm2 oncogene, which can involve p53 indirectly. The partial SGH-coding sequence of mdm2 and DCC was determined. K-ras mutation in the second position of codon 12 was present in 17 of 19 (90%) of tumors. Immunohistochemistry and single strand conformation polymorphism analysis showed no evidence of p53 mutation in 21 tumors. RNase protection assays showed overexpression of mdm2 in 5 of 19 (26%) tumors. Semiquantitative reverse transcription-PCR analysis showed a complete or partial loss of DCC expression in 10 of 19 (53%) neoplasms and of Rb-1 (42%) expression in 8 of 19 tumors when compared to matched controls. Deregulation of these genes appears to be significant in SGH pancreatic carcinogenesis as indicated by their frequencies. However, the fact that 6 tumors showed either only a K-ras mutation or the absence of alterations of the 5 genes analyzed indicates that additional as yet unstudied or unknown genes are also involved in SGH pancreatic duct carcinogenesis.
...
PMID:Multiple genetic alterations in hamster pancreatic ductal adenocarcinomas. 778 Sep 69

8-Oxo-7,8-dihydroguanosine triphosphate (8-oxo-dGTP) is formed from the oxidation of GTP in the nucleotide pools of cells during normal cellular metabolism and from exogenous sources. 8-Oxo-dGTP is a potent mutagenic substrate for DNA synthesis causing transversion mutations. In human cells this oxidized base is hydrolyzed to 8-oxo-7,8-dihydroguanosine monophosphate by 8-oxo-7,8-dihydroguanosine triphosphatase (8-oxo-dGTPase) to prevent the misincorporation of 8-oxo-dGTP into cellular DNA. In order to better understand specific human tissue and cell type responses to oxidative stress, we used colorimetric in situ hybridization, with an 8-oxo-dGTPase-specific antisense oligomer probe, to map, for the first time, the cellular distribution of 8-oxo-dGTPase mRNA in tissue sections of normal neonatal foreskin and adult human breast tissues. Paraffin embedded tissue sections were hybridized with a digoxigenin-labeled 39 base oligomer, antisense to 8-oxo-dGTPase cDNA. Hybridization of the probe to cells expressing the 8-oxo-dGTPase gene was visualized following immunodetection with an alkaline phosphatase-conjugated anti-digoxigenin antibody. Following color development, we were able to simultaneously identify tissue architecture and cell types with expression of the 8-oxo-dGTPase gene. There was no hybridization-specific color when sections were 'mock' hybridized, hybridized with a sense probe or treated with RNase. In skin dermis, fibroblasts express high levels of 8-oxo-dGTPAse mRNA. Within the epidermis, a gradient of expression was observed, from high to moderate levels in the replicating basal epithelial cells to undetectable in the non-mitotic suprabasal and granular epithelial cells. In the breast tissue, fibroblasts in the loosely connective tissue and myoepithelial cells expressed high levels of 8-oxo-dGTPase mRNA, while expression in the luminal epithelial cells was not detectable. Our data suggest that expression of 8-oxo-dGTP is heterogenous between cell types within an organ and may help to explain cell type-specific responses to oxidative stress, especially in replicating and potentially replicating cells with low levels of this protective protein.
Carcinogenesis 1995 Feb
PMID:Cell type-specific expression of human 8-oxo-7,8-dihydroguanosine triphosphatase in normal breast and skin tissues in vivo. 785 59

Renal alpha-protein kinase C (PKC) is rapidly down-modulated modulated in animals treated with the renal toxin and tumor promoter, folic acid (Dong et al., Cancer Res., 53: 4542-4549, 1993). To further explore the role of PKC isozymes in renal growth and carcinogenesis, we compared phorbol ester receptor and PKC isozyme content, distribution, and regulation in primary and oncogene-altered rat renal proximal tubule epithelial cells (RPTE) in culture. Immunoblot analysis and RNase protection assays indicated that RPTE expressed at least four PKC isozymes, alpha, delta, epsilon, and zeta. Total phorbol ester receptors were decreased in primary proliferating, E1A-immortalized, and SV40-transformed RPTE compared to primary quiescent RPTE. The decrease in PDBu binding was largely due to a specific decrease in alpha-PKC protein content to approximately 50% of the level in quiescent RPTE. Degradation rates and message levels were compared to determine the mechanism for the decrease in alpha-PKC. Whereas alpha-PKC message levels in quiescent and proliferating primary RPTE were comparable, alpha-PKC degradation was increased in proliferating cells. These results indicate that the decreased alpha-PKC content was due largely to increased turnover. Phorbol ester stimulated the rate of degradation, thus demonstrating a link between degradation rate and PKC activation. These results suggest that the increased basal degradation rate in proliferating and oncogene-altered cells reflects an increase in activity of PKC in these cells.
...
PMID:Protein kinase C isozyme expression and down-modulation in growing, quiescent, and transformed renal proximal tubule epithelial cells. 798 53


<< Previous 1 2 3 4 5 6 7 Next >>

---