Human oligodendrocyte progenitor cells mediate synapse elimination through TAM receptor activation

Oligodendrocyte progenitor cells (OPCs) have been implicated in synaptic remodelling in animal models, but the underlying mechanisms and their relevance to human brain development remain unclear. Here, we generate a human multi-lineage forebrain organoid model in which OPCs, together with microglia, form close contacts with synapses and spontaneously internalize synaptic material. Single-nucleus transcriptomic profiling with unbiased cell-cell communication analysis identifies the growth arrest-specific gene 6 (GAS6)-TYRO3, AXL, and MERTK (TAM) receptor axis as a key signalling pathway, with neurons and microglia expressing GAS6 and a subset of OPCs expressing AXL. Further, dose-dependent pharmacological inhibition of TAM receptors demonstrates the importance of AXL, and targeted reduction of AXL expression in OPCs impairs synaptic uptake. These findings reveal a role for GAS6-AXL signalling in driving synaptic internalisation by AXL+ OPCs during early human brain development.