OBJECTIVETo observe the cellular uptake of beta amyloid protein (Abeta) by cultured human neuroblastoma (SH-SY5Y) cells and the location of Abeta in the subcellular structures.

METHODSThe time course of cellular uptake of Abeta1-42-fluo in the SH-SY5Y cells was observed directly under laser scanning confocal microscope (LSCM). Image analysis was conducted to compare the differences of cellular Abeta uptake after treatment of the cells with different concentrations of extracellular Abeta for 24 h. Multiple immunofluorescence staining was employed to identify the location of Abeta in the subcellular structures.

RESULTSSH-SY5Y cells showed Abeta internalization after incubation with Abeta1-42-fluo (200 nmol/L) for 1 h, and the quantity of Abeta uptake was time-dependent. A higher concentration of extracellular Abeta1-42-fluo resulted in increased Abeta uptake, which differed significantly between the 3 groups with treatment at different concentrations (P<0.01 or 0.05). Immunofluorescence staining revealed a co-localization of part of the Abeta and Lamp-1 (a lysosome marker) in the cytosome.

CONCLUSIONSH-SY5Y cells can clear Abeta through a time- and dose-dependent cellular uptake mechanism. Part of the Abeta uptaken in the cytoplasm is located in the lysosome .