Fig. 1.

Signaling pathways involved in microglial phagocytosis. A Extracellular nucleotides, such as UDP and UTP, trigger microglial phagocytosis through P2Y6R/PLC/InsP3 pathway. B Apoptotic debris induces phagocytosis via TREM-2/DAP12/ERK/PKC pathway. C Endogenous or ectogenic detriments, such as LPS, viral nucleotides, α-synuclein, and f-Aβ, provoke phagocytosis by microglia via TLRs through activation of MyD88-dependent IRAK4/p38/scavenger receptors pathway or MyD88-independent actin-Cdc42/Rac signaling pathway