Subcellular sequencing of single neurons reveals the dendritic transcriptome of GABAergic interneurons

Abstract

The localization and translation of mRNAs to dendrites and axons maintains and modifies the local proteome of neurons, and is essential for synaptic plasticity. Although significant efforts have allowed the identification of localized mRNAs in excitatory neurons, it is still unclear whether interneurons also localize a large population of mRNAs. In addition, the variability in the population of localized mRNAs within and between cell-types is unknown. Here we developed a method for the transcriptomic characterization of a single neurons subcellular compartments, which combines laser capture microdissection with scRNA-seq. This allowed us to separately profile the dendritic and somatic transcriptomes of individual rat hippocampal neurons and investigate the relation in mRNA abundances between the soma and dendrites of single glutamatergic and GABAergic neurons. We identified two types of glutamatergic and three types of GABAergic interneurons and we found that, like their excitatory counterparts, interneurons contain a rich repertoire of ~4000 mRNAs. The individual somatic transcriptomes exhibited more cell type-specific features than their associated dendritic transcriptomes. The detection and abundance of dendritic mRNAs was not always simply predicted by their somatic counterparts. Finally, using cell-type specific metabolic labelling of isolated neurites, we demonstrated that the processes not only of Glutamatergic but also of GABAergic neurons are capable of local translation, suggesting mRNA localization and local translation is a general property of neurons.