Neuronal ApoE Regulates the Cell-to-Cell Transmission of α-Synuclein

Abstract

The presence of protein inclusions, called Lewy bodies (LBs) and Lewy neurites (LNs), in the brain is the main feature of Parkinson's disease (PD). Recent evidence that the prion-like propagation of alpha-synuclein (alpha-syn), as a major component of LBs and LNs, plays an important role in the progression of PD has gained much attention, although the molecular mechanism remains unclear. In this study, we evaluated whether neuronal ApoE regulates the cell-to-cell transmission of alpha-syn and explored its molecular mechanism using in vitro and in vivo model systems. We demonstrate that neuronal ApoE deficiency attenuates both alpha-syn uptake and release by downregulating LRP-1 and LDLR expression and enhancing chaperone-mediated autophagy activity, respectively, thereby contributing to alpha-syn propagation. In addition, we observed that alpha-syn propagation was attenuated in ApoE knockout mice injected with pre-formed mouse alpha-syn fibrils. This study will help our understanding of the molecular mechanisms underlying alpha-syn propagation.