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:3.1.27.4 (ribonuclease)
6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deposition of amyloid beta-protein in senile plaque cores and cerebral vessels is a major neuropathological finding of Alzheimer's disease (AD). Three species of cDNA clones encoding amyloid beta-protein precursors (APP 695, APP 751 and APP 770) were isolated and sequenced. We examined quantitatively the expression of these APP mRNAs in autopsied brains (frontal cortex) of AD patients and control subjects, using Northern blot analysis and the ribonuclease protection assay. Northern blot analysis revealed the production of three types of APP mRNA in the human brain and that AD/control ratios were 2.04 for APP 770 mRNA, 1.11 for APP 751 mRNA and 1.12 for APP 695 mRNA. In the protection assay the ratio of APP 770/APP 751/APP 695 mRNA was approximately 1:10:20 in the brain of control and the AD/control ratios were 2.38, 1.30 and 0.81 for APP 770, APP 751 and APP 695 mRNAs, respectively. These results suggested that an increase in APP 770 and APP 751, harboring a protease inhibitor domain, may disturb the balance between biosynthesis and degradation of APPs, which might lead to amyloid deposition.
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PMID:[Expression of amyloid beta-protein gene in Alzheimer's disease]. 211 40

Recent studies have indicated a normal gene dose for the amyloid precursor protein (APP) in Alzheimer's disease (AD). These findings leave open the possibility that elevated levels of messenger RNA (mRNA) for this protein may contribute to the pathogenesis of AD. Using Northern analysis, we compared the levels of mRNA for the APP and 3 cytoskeletal proteins in parietal cortex of 6 brains having marked AD-type degeneration with the levels of these mRNAs in 6 control samples. The cytoskeletal mRNAs studied were those for the human neurofilament 68-kDa subunit (HNFL), for alpha-tubulin, and for glial fibrillary acidic protein (GFAP). A ribonuclease (RNase) protection assay was also used to compare AD and control HNFL mRNA levels. The mRNAs for APP, HNFL, and alpha-tubulin were diminished in AD cortex. The decrement for APP mRNA was less than that for HNFL or alpha-tubulin. The message for GFAP in AD cortex showed no loss. The findings support a general deficit in neuronal mRNAs, including that for APP. They do not exclude the possibility of elevated levels of the message for the APP in small neuronal subsets, in subcortical neurons projecting to cortex, or as a generalized phenomenon in earlier stages of the disease.
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PMID:Altered expression of genes for amyloid and cytoskeletal proteins in Alzheimer cortex. 246 80

Expression of three types of mRNA encoding amyloid beta-protein precursor (APP) in various tissues was analysed, using a ribonuclease protection assay, with special reference to Alzheimer's disease (AD). The total content and the proportion of APP mRNAs were specific to each tissue. Among eight tissues examined, the brain was distinct in that the expression level was highest and APP695 mRNA was expressed in abundance. The ratio of APP770/APP751/APP695 mRNAs was approximately 1:10:20 in the cerebral cortex of control brain. The proportions of APP770 mRNA and APP770-plus-APP751 mRNAs increased up to 2.6- and 1.4-fold, respectively, in various regions of AD brain compared with control. The enhanced expression of protease inhibitor-harboring types (APP770 and APP751) may disturb the balance between biosynthesis and degradation of APPs and ultimately lead to accumulation of beta-protein as amyloid.
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PMID:Tissue-specific expression of three types of beta-protein precursor mRNA: enhancement of protease inhibitor-harboring types in Alzheimer's disease brain. 251 87

Recent progresses in DNA technology have made DNA diagnosis possible in clinical laboratories. The diagnosis is characterized by a potential to unveil genetic abnormalities and dispositions in the absence of symptoms, using any tissues not directly affected. Routinization of DNA diagnosis requires nonradioactive probes with sufficient sensitivities for detection and automated systems to use them. These requirements are being met by the latest technology such as polymerase chain reaction (PCR) and time-controlled temperature cyclers. Nonradioactive probes commercially available today, as tested in our laboratory, are not sensitive enough for practical use in single-copy gene analysis, unless combined with PCR. DNA diagnosis is extending to analyses of cDNA or mRNA. Our recent studies using a Northern blot technique and a ribonuclease protection assay indicated that the expression of mRNAs for those amyloid beta-protein precursors that harbor a protease inhibitor increases in the brain of Alzheimer's disease patients.
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PMID:[DNA diagnosis and laboratory tests]. 268 98

It has been suggested that defects in the relationship between ribonuclease and its proteinaceous inhibitor could be a contributory factor in Alzheimer's disease. We have investigated this possibility further by analysing free and bound enzyme activities and the activity of the inhibitor in nine regions of diseased and normal brain. These were chosen to include areas known to be affected by the disease, regions not histologically affected but thought to be involved in the disease process, and areas not thought to be involved in the disease. Neither the enzyme nor its inhibitor is defective in its activities in the chosen areas of Alzheimer's disease brain when compared with those of carefully age-matched controls.
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PMID:Role of ribonuclease and ribonuclease inhibitor activities in Alzheimer's disease. 279 4

Levels of free and total alkaline ribonuclease, and levels of acidic ribonuclease, were measured postmortem in control brains and in the brains of patients with Alzheimer's disease. In each brain region assayed, whether control or Alzheimer's, there was a statistically significant difference between the levels of free and total alkaline ribonuclease. Between 59 and 90% of the enzyme activity was associated with alkaline ribonuclease inhibitor in an inactive complex. Levels of free and total alkaline ribonuclease varied widely among different brains and brain regions, and were always lower in cerebellum than in temporal cortex and occipital pole. There was no significant difference in the levels of total alkaline ribonuclease, free alkaline ribonuclease, or acidic ribonucleases between corresponding regions of Alzheimer's and control brains. There was also no qualitative difference in the subcellular distribution of the alkaline and acidic ribonucleases between Alzheimer's and control brain. No significant relationships were found between ribonuclease levels and age, neuritic plaque density, postmortem interval, or storage time.
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PMID:Ribonuclease activities and distribution in Alzheimer's and control brains. 292 89

A macromolecular alteration occurs at the posttranscriptional level in the Alzheimer's disease (AD) brain. Compared with age-matched controls, total cellular RNA and polyadenylated RNA were substantially reduced in the AD cortex with many neuritic plaques and neurofibrillary tangles. RNA changes are associated with a significant increase in alkaline ribonuclease activity due to an abnormality in the ribonuclease-inhibitor complex. The decrease in protein synthesis in the AD brain, previously observed in patients severely affected with AD, and in translation systems in vitro with AD cortical messenger RNA, may be partly related to an enzyme-inhibitor alteration that affects RNA levels and activity. Decreased protein synthesis therefore may contribute to the characteristic decline in certain neurotransmitter enzymes and to the loss of neurons in the AD brain.
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PMID:Alzheimer's disease brain: alterations in RNA levels and in a ribonuclease-inhibitor complex. 620 67

Several reports indicate that Alzheimer disease (AD) brain contains elevated levels of heat shock 70 proteins. To determine the cellular localization of the heat shock 70 mRNAs, specific oligonucleotide probes were in situ hybridized to AD and control brains. When oligonucleotides were in situ hybridized to brain sections with no AD neuropathology, hybridization was cell-specific and prior ribonuclease (RNase) treatment of adjacent sections resulted in no hybridization signal. However, in situ hybridization to AD hippocampus resulted in heavy grain deposition over senile plaques and neurofibrillary tangles. Despite altering a number of experimental variables, we observed a similar pattern of grain deposition with most of the oligonucleotides tested, including one oligonucleotide specific for glutamic acid decarboxylase mRNA. In situ hybridization with either an RNA probe for glutamic acid decarboxylase or an oligonucleotide probe specific for 18S rRNA did not show this pattern of grain deposition. In control studies a sense hsc70 oligonucleotide showed no grain deposition in either cerebellum or hippocampus. Sections from AD hippocampus pretreated with RNase prior to in situ hybridization demonstrated enhanced grain deposition with the majority of probes tested. Anomalous in situ hybridization to AD hippocampus was usually eliminated by removing formamide from the posthybridization washes, although post-RNase sticking often remained intense. These findings indicate that artifactual probe binding to senile plaques and neurofibrillary tangles may complicate the analysis of in situ hybridization studies using oligonucleotide probes to determine mRNA distribution in AD brain.
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PMID:Anomalous binding of radiolabeled oligonucleotide probes to plaques and tangles in Alzheimer disease hippocampus. 791 65

Nonenzymatic glycation (Maillard reaction) of long-lived proteins is a major contributor to the pathology of diabetes and possibly aging and Alzheimer's disease. We report here kinetic studies of the glycation of the model protein ribonuclease A by glucose and ribose leading to the formation of antigenic advanced glycation end products ("AGEs"), detectable by AGE-specific polyclonal antibodies, and pentosidine, an acid-stable fluorescent AGE. As anticipated, the kinetics of glycation by ribose were considerably faster than by glucose, and the rate of AGE formation initially increased with increasing sugar concentrations. However, ribose above 0.15 M appeared to paradoxically slow the kinetics of AGE formation, suggesting ribose inhibits the conversion of "early" Amadori rearrangement products to "late" AGEs and thus favors the accumulation of reactive Amadori intermediates. The facile isolation of such protein intermediates was achieved by an "interrupted glycation" protocol which free and reversibly bound (Schiff base) ribose was removed following a short (24h) initial incubation of 0.5 M ribose at 37 degrees C. The kinetics of buildup of the Amadori intermediates and the kinetics of their post-Amadori conversion to antigenic AGEs were independently studied. A rapid and reversible inhibition of the post-Amadori kinetics by free ribose was verified by direct re-addition of ribose to the isolated, sugar-free intermediate. The pH dependence of the kinetics of antigenic AGE formation from such intermediates was measured and exhibited an unusual bell-shaped profile over the pH range of 5.0-9.5 with a maximum near pH 8.0. Aminoguanidine, a pharmacological AGE inhibitor, was found to moderately or weakly inhibit antigenic AGE formation in such post- Amadori steps. The isolation of the glycated ribonuclease intermediate thus simplifies kinetic and mechanistic studies of AGE formation, permits AGE studies in the absence of complications arising from free or Schiff base bound sugar, and provides a novel methodology for evaluating the mechanism and efficacy of therapeutic agents that may inhibit AGE formation.
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PMID:Kinetics of nonenzymatic glycation of ribonuclease A leading to advanced glycation end products. Paradoxical inhibition by ribose leads to facile isolation of protein intermediate for rapid post-Amadori studies. 866 53

The non-Abeta component of Alzheimer's disease amyloid precursor protein (NACP) is predominantly a neuron-specific presynaptic protein that may play a central role in neurodegeneration because NACP fragments are found in Alzheimer's disease amyloid and a mutation in the NACP gene is associated with familial Parkinson's disease. In addition, NACP may play an important role during synaptogenesis and CNS development. To understand better the patterns of NACP expression during development, we analyzed the levels of this protein as well as the levels of another synaptic protein (synaptophysin) by ribonuclease protection assay, western blotting, and immunocytochemistry in fetal, juvenile, and adult mouse brain. From embryonic day 12 to 15, there was a slight increase, which was then followed by a more dramatic increase at later time points. Immunocytochemical staining for NACP increases throughout these stages as well. Although NACP appeared early in CNS development, synaptophysin levels started to rise at a later stage. These findings support the contention that NACP might be important for CNS development. Furthermore, the cytosolic component of NACP precedes the particulate component in development, indicating that a redistribution of the protein to the membrane fraction may be important for events later in neuronal development and in synaptogenesis.
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PMID:Expression pattern of synucleins (non-Abeta component of Alzheimer's disease amyloid precursor protein/alpha-synuclein) during murine brain development. 964 83


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