Activity-dependent Golgi satellite formation in dendrites reshapes the neuronal surface glycoproteome
Activity-driven changes in the neuronal surface glycoproteome are known to occur with synapse formation, plasticity and related diseases, but their mechanistic basis and significance are unclear. Here, we observed that N-glycans on surface glycoproteins of dendrites shift from immature to mature forms containing sialic acid in response to increased neuronal excitation. In exploring the basis of these N-glycosylation alterations, we discovered they result from the growth and proliferation of Golgi satellites scattered throughout the dendrite. Golgi satellites that formed with neuronal excitation were in close association with ER exit sites and early endosomes and contained glycosylation machinery without the Golgi structural protein, GM130. They functioned as distal glycosylation stations in dendrites, terminally modifying sugars either on newly synthesized glycoproteins passing through the secretory pathway, or on surface glycoproteins taken up from the endocytic pathway. These activities led to major changes in the dendritic surface of excited neurons, impacting binding and uptake of lectins, as well as causing functional changes in neurotransmitter receptors such as nicotinic acetylcholine receptors. Neural activity thus boosts the activity of the dendrites satellite micro-secretory system by redistributing Golgi enzymes involved in glycan modifications into peripheral Golgi satellites. This remodeling of the neuronal surface has potential significance for synaptic plasticity, addiction and disease.