Mammalian glial protrusion transcriptomes predict localization of Drosophila glial transcripts required for synaptic plasticity

The polarization of cells often involves the transport of specific mRNAs and their localized translation in distal projections. Neurons and glia both contain long cytoplasmic processes with important functions. While mRNA localization has been studied extensively in neurons, little is known in glia, especially in intact nervous systems. Here, we predicted 1700 localized Drosophila glial transcripts by extrapolating from our meta-analysis of 8 existing studies characterizing the localized transcriptomes and translatomes of synaptically-associated mammalian glia. We tested these predictions in glia of the neuromuscular junction of Drosophila larvae and found that localization to vertebrate glia is a strong predictor of mRNA localization of the high confidence Drosophila homologues. We further showed that some of these localized transcripts are required in glia for plasticity of neuromuscular junction synapses. We conclude that peripheral glial mRNA localization is a common and conserved phenomenon and propose that it is likely to be functionally important.