| Alzheimer's disease (AD) is a neurodegenerative disease. The clinical features of AD are characterized by progressive memory loss and dementia, finally resulting in death. Three significant neuropathological findings were detected by studying pathological alteration in the AD brain. One is the deposition of β-amyloid peptide (Aβ) which forms neuritis plaques outside of neurons, the second is neurofibrillary tangles (NFT) within neurons, the third is primary degeneration of neurons. However, up to now the relative mechanism is still unclear. The increasing evidences had shown that missense mutations of presenilin-1 (PS-1) gene could be the most common cause resulting in early-onset familial Alzheimer's disease (EOFAD). Unfortunately, the further and detail mechanisms by which this mutations cause the cognitive impairment, a characteristic phenomenon of AD, are unknown. The existed data had confirmed that presenilin-1 is a multiple transmembrane protein, and when the mutations of presenilin-1 occurs, as a result, it will resulted in proteolysis cleavage of several proteins, such as β-APP and Notch and so on, within the transmembrane domains by modulating activity of γ-secretase, and further lead to dysfunction and apoptosis of involved cells. We had previously studied the effect of mutated presenilin-1 (PS-1) gene on the growth, proliferation and differentiation, morphology and enzyme activity changes of ChAT and AchE of PC12 induced by RA (we call it as "modeled cell") by transfected mutant PS-1 and wild-type PS-1 into them. Our results confirmed that the mutant PS-1 resulted in a marked inhibition of proliferation and differentiation of modeled cells, and decreased the enzyme activity of ChAT and AchE, and finally induced apoptosis of cells. These results offered more evidences that there is a marked relation between the mutation of PS-1 and AD arising and developing, furthermore, these results also made it a possible to further expose and investigate for likely new or relative duty gene involving in AD due to PS-1 mutation. In order to find out the relative duty genes which induced cell apoptosis by PS-1 mutation, at present study, the gene differences expression of gene engineered PC12 cells after transfected the mutant PS-1 and wild-type PS-1 gene respectively was investigated by differential display technique. Based on the getting positive cells clones which steadily expressed mutant PS-1 and wild-type PS-1, we designed three anchored oligo(dT) primers and 8 arbitrary primers for RT-PCR, and then the products of PCR were separated by PAGE (polyacrylamided gel electrophoresis). In contrast to traditional radiography display, a silver staining was used in differential display. We detected that the silver staining used in differential display can also display the DNA electrophoresis bands clearer. Moreover, it doesn't influence the following experiment, such as recover, re-amplificated, clone, and sequence of DNA bands. At the same time, this technique avoids some potential harm from radioactivity. In contrast to traditional radiography display, the displayed bands can be directly cut and recovered conveniently from gel after electrophoresis. It is a beneficial, useful and worthy of spread method that silver staining is used in differential display.In our study, the total of 31 differential bands had been successfully recovered, re-amplified, cloned them into T vector and sequenced. The 8 fragments that have were selected from the 31 bands for further analysis by reverse Northern blots. Six out of 8 bands were confirmed in reverse Northern Blot. Two confirmed fragments shown higher expression in cells expressing mutant PS-1 than that in cells expressing wild-type PS-1. Another 4 confirmed fragments shown higher expression in cells expressing wild-type PS-1 than that in cells expressing mutant PS-1. However, in another 2 out of 8 differential bands, one was positive and not significant expression change between two kinds of cells, the other was negative in the two kinds of cells.The fragments...
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