Autophagy is involved in oligodendroglial precursor-mediated clearance of amyloid peptide

Background: Accumulation of beta-amyloid peptides is an important hallmark of Alzheimer's disease (AD). Tremendous efforts have been directed to elucidate the mechanisms of beta-amyloid peptides degradation and develop strategies to remove beta-amyloid accumulation. In this study, we demonstrated that a subpopulation of oligodendroglial precursor cells, also called NG2 cells, were a new cell type that can clear beta-amyloid peptides in the AD transgene mice and in NG2 cell line. Results: NG2 cells were recruited and clustered around the amyloid plaque in the APPswe/PS1dE9 mice, which is Alzheimer's disease mouse model. In vitro, NG2 cell line and primary NG2 cells engulfed beta-amyloid peptides through the mechanisms of endocytosis in a time dependent manner. Endocytosis is divided into pinocytosis and phagocytosis. A beta(42) internalization by NG2 cells was mediated by actin-dependent macropinocytosis. The presence of beta-amyloid peptides stimulated the autophagic pathway in NG2 cells. Once inside the cells, the beta-amyloid peptides in NG2 cells were transported to lysosomes and degraded by autophagy. Conclusions: Our findings suggest that NG2 cells are a new cell type that can clear beta-amyloid peptides through endocytosis and autophagy.