Research Article

Increasing Membrane Cholesterol Level Increases the Amyloidogenic Peptide by Enhancing the Expression of Phospholipase C

Figure 2

Elevation of PIP2 level prevented the effect of cholesterol on Aβ42 production. (a) Incubating APP-transfected HeLa cells with water-soluble cholesterol did not significantly change the full-length APP level. Cells were incubated with 75 μM water-soluble cholesterol for 8 h. Similar Western blotting results were obtained from 4 different experiments. (b) Both sAPPα and sAPPβ were slightly increased by incubating cells with 75 μM water-soluble cholesterol for 8 h ( ). The levels of sAPPα and sAPPβ were measured from the conditioned media as described in Section 2. (c) Supplying PIP2 decreased Aβ42 production and prevented the effect of cholesterol. APP-transfected HeLa cells were incubated with 0, 2, and 5 μM carrier-PIP2 complex in the absence and the presence of 75 μM water-soluble cholesterol for 4 h. Aβ42 levels were measured from the conditioned media by using ELISA method. Without treating cells with water-soluble cholesterol, Aβ42 production decreased as PIP2 concentration increased ( , open bars). As expected, treating cells with water-soluble cholesterol increased the production Aβ42 in the absence of PIP2 (the first closed bar). However, the effects of cholesterol on Aβ42 were prevented by the presence of 2 μM and 5 μM PIP2 (the second and the third close bars, ). (d) Elevation of PIP2 level did not change Aβ40 production ( ). *** .