シクロフィリンAは脳ペリサイトにおけるクラスリン依存性エンドサイトーシスによるα-Syn取り込みに関与する

抄録

Parkinson’s disease (PD) is characterized by widespread distribution of Lewy bodies, which are mainly composed of aggregated α-synuclein(α-Syn), in the brain. We previously revealed that pericytes, one of the blood-brain barrier-constituting cells, take up α-Syn and degrade it. Therefore, an efficient uptake of a-Syn by pericytes enable to establish a novel disease modifying therapy of PD utilizing the α-Syn d　egradation system in pericytes. In this study, we investigated the intracellular uptake mechanism in pericytes for α-Syn.

We used primary cultures of rat brain pericytes. Increasing concentrations of extracellular α-Syn ranging from 0.05 to 10 μg/mL resulted in the increased cellular accumulation of α-Syn in pericytes. The cell/medium ratio of α-Syn in pericytes showed a significant decrease with the increased concentration of extracellular α-Syn. Furthermore, the uptake of α-Syn by pericytes was decreased at 4˚C and in the presence of chlorpromazine. Cyclosporin A(CsA), a P-glycoprotein (P-gp) inhibitor, increased the uptake of α-Syn by pericytes. However, siRNA-mediated knockdown of P-gp failed to increase the uptake of α-Syn by pericytes. Knockdown of cyclophillin A (CypA), a molecular target of CsA to inhibit calcineurin activity, decreased the uptake of α-Syn by pericytes.

These results suggest that α-Syn uptake by pericytes is mediated by saturable transport system, clathrin-mediated endocytosis, and a CypA-dependent mechanism. In addition, inhibiting calcineurin activity would contribute to the enhanced α-Syn uptake, leading to α-Syn degradation by pericytes.