Table 1.

Signaling involved in microglia-mediated synaptic pruning

Signaling	Effects on pruning	Specificity	Reference
Microglial C3, C1q and CR3 (“EAT ME”)	Enhance	Apoptotic, weak or inactive synapses; activity-dependent	Shi et al., 2015; Fonseca et al., 2017; Györffy et al., 2018; Weinhard et al., 2018; Anderson et al., 2019; Wang et al., 2020
Neuronal CD47 and microglial SIRPα (“DON’T EAT ME”)	Inhibit	Strong or active synapses	Lehrman et al., 2018
Neuronal CD200 and microglial CD200R	Inhibit	Strong synapses	Lyons et al., 2017
Neuronal CX3CL1 and microglial CX3CR1	Enhance	Weak or immature synapses	Gunner et al., 2019; Nemes-Baran et al., 2020
Microglial TREM2	Enhance	Apoptotic or immature synapses	Filipello et al., 2018
Neuronal phosphatidylserine	Enhance	Apoptotic or immature synapses	Scott-Hewitt et al., 2020

C3: Complement Component 3; C1q: Complement component 1 Q subcomponent; CR3: complement receptor 3; CD47: cluster of differentiation 47; CD200: cluster of differentiation 200; CD200R: cluster of differentiation 200 receptor; CX3CL1: C-X3-C motif chemokine ligand 1; CX3CR1: C-X3-C motif chemokine receptor 1; SIRPα: signal regulatory protein alpha; TREM2: triggering receptor expressed on myeloid cells 2.